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This thesis present research on synthesis, microstructure, and properties of carbide- and boride- based thin films. The films have been synthesized by dc magnetron sputtering, and their microstructures have been characterized mainly by X-ray photoelectron spectroscopy (XPS), X-ray diffraction, and transmission electron microscopy. One of the main objectives with this research has been to evaluate the thin films potential as materials for sliding electrical contact applications and this have influenced, which properties that have been evaluated. Co-sputtered Nb-C films have a microstructure comprising of nanocrystalline NbCx (nc-NbCx) grains embedded in a matrix of amorphous C (a-C). A thinner a-C matrix form in the Nb-C films compared to the well-studied Ti-C system. As a consequence, the Nb-C films have a higher hardness and conductivity than previously studied Ti-C sputtered under similar conditions. The promising electrical contact properties are attained for reactively sputtered Nb-C films under industrial conditions, at deposition rates two orders of magnitude higher. A reduction in crystallinity is seen when Si is added to the Nb-C films and amorphous films forms at Si content > 25 at.%. The alloying of Si was however not beneficial for the electrical contact properties. Substoichiometric CrB2-x (B/Cr = 1.5) and NbB2-x (B/Nb = 1.8) films are achieved when deposited from MeB2 targets. Boron segregates to grain boundaries forming a B-rich tissue phase. This result in superhardness for the NbB2-x films (42 ± 4 GPa) as well as a low friction attributed to the formation of a boric acid film. Carbon forms a solid solution in the MeB2 grains as well as segregating to grain boundaries forming an amorphous BCx (a-BCx) phase when alloyed to CrB2-x and NbB2-x films. The formation of the a-BCx phase drastically improves the electrical contact resistance of the NbB2-x films. However, the mechanical properties are degraded, which result in a high friction and wear rate

The potential for tuning of magnetic properties and the exceptional uniformity are among the features that make amorphous magnetic materials attractive for technology. Here it is shown that the magnetization reversal in amorphous SmCo thin films takes place through the formation of giant magnetic domains, over a centimeter across. The domain structure is found to be dictated by the direction of the imprinted in-plane easy axis and the film boundaries. This is a consequence of the size of the anisotropy and the structural uniformity of the films, which also allows the movement of millimeter-long domain walls over distances of several millimeters. The results demonstrate the possibility of tailoring the magnetic domain structure in amorphous magnets over a wide range of length scales, up to centimeters. Moreover, they highlight an important consequence of the structural perfection of amorphous films.

X-ray absorption near-edge structure (XANES) spectroscopy has been applied to characterize the phase evolution of Ag–TiO2 films subjected to annealing treatments up to 1000 C. Silver has been theoretically predicted as a rutile promoter in anatase powders lowering the transition temperature, however, no systematic studies on films have been reported yet. In this work, the Ti L2,3- and O K-edge in XANES spectra were used as fingerprints of the phase structure of the films. The results show that silver atoms strongly affect the transition of the initially amorphous films to the anatase structure, delaying the crystallization temperature up to 400 C and, at the same time, promoting the subsequent phase transformation from anatase to rutile at temperatures as low as 600 C. These results have been confirmed by X-Ray Diffraction (XRD) analysis as well as by High Resolution TEM images (HRTEM) of films.

Next generation Li-ion batteries (LIB) are expected to display high power densities (i.e. high rate performance, or fast energy storage) while maintaining high energy densities and stable cycling performance. The key to fast energy storage is the efficient management of electron conduction, Li diffusion, and Li-ion migration in the electrode systems, which requires tailored material and structural engineering in nanometer scale. Atomic layer deposition (ALD) is a unique technique for nanostructure fabrications due to its precise thickness control, unprecedented conformality, and wide variety of available materials. This research aims at using ALD to fabricate materials, electrodes, and devices for fast electrochemical energy storage. First, we performed a detailed study of ALD V2O5 as a high capacity cathode material, using vanadium tri-isopropoxide (VTOP) precursor with both O3 and H2O as oxidant. The new O3-based process produces polycrystalline films with generally higher storage capacity than the amorphous films resulting from the traditional H2O-based process. We identified the crucial tradeoff between higher gravimetric capacity with thinner films and higher material mass with thicker films. For the thickness regime 10-120 nm, we chose areal energy and power density as a useful metric for this tradeoff and found that it is optimized at 60 nm for the O3-VTOP ALD V2O5 films. In order to increase material loading on fixed footprint area, we explored various 3-dimentional (3D) substrates. In the first example, we used multiwall carbon nanotube (MWCNT) sponge as scaffold and current collector. The core/shell MWCNT/V2O5 sponge delivers a stable high areal capacity of 816 μAh/cm2 for 2 Li/V2O5 voltage range (4.0-2.1 V) at 1C rate (nC means charge/discharge in 1/n hour), 450 times that of a planar V2O5 thin film cathode. Due to low density of MWCNT and thin V2O5 layer, the sponge cathode also delivers high gravimetric power density in device level that shows 5X h

Two series of Nb-Si-C thin films of different composition have been deposited using DC magnetron sputtering. In the first series the carbon content was kept at about 55 at.% while the Si/Nb ratio was varied and in the second series the C/Nb ratio was varied instead while the Si content was kept at about 45 at.%. The microstructure is strongly dependent on Si content and Nb-Si-C films containing more than 25 at.% Si exhibit an amorphous structure as determined by X-ray diffraction. Transmission electron microscopy, however, induces crystallisation during analysis, thus obstructing a more detailed analysis of the amorphous structure. X-ray photo-electron spectroscopy suggests that the amorphous films consist of a mixture of chemical bonds such as Nb-Si, Nb-C, and Si-C. The addition of Si results in a hardness decrease from 22 GPa for the binary Nb-C film to 18 - 19 GPa for the Si-containing films, while film resistivity increases from 211 mu Omega cm to 3215 mu Omega cm. Comparison with recently published results on DC magnetron sputtered Zr-Si-C films, deposited in the same system using the same Arplasma pressure, bias, and a slightly lower substrate temperature (300 degrees C instead of 350 degrees C), shows that hardness is primarily dependent on the amount of Si-C bonds rather than type of transition metal. The reduced elastic modulus on the other hand shows a dependency on the type of transition metal for the films. These trends for the mechanical properties suggest that high wear resistant (high H/E and H-3/E-2 ratio) Me-Si-C films can be achieved by appropriate choice of film composition and transition metal.

We report on the effect of carbon implantation on the structural, electronic, and magnetic properties of Fe93Zr7 (FeZr) amorphous films. Extended X-ray absorption fine structure measurements on (FeZr)(100-x)C-x (x = 0, 5.5, and 11) indicate the incorporation of carbon in the FeZr matrix, with an increase of the Fe-Fe distance by implanting carbon. X-ray photoelectron spectroscopy measurements reveal the creation of Fe-C bonds after implantation. A significant enhancement of the Curie temperature and decrease of the coercivity are observed in the carbon-implanted films. Moreover, the non collinear ferromagnetism of the as-grown FeZr film diminishes upon carbon implantation., QC 20130627

Mg@ZnO thin films were prepared by DC/RF magnetron co-sputtering in (N2+O2) ambient conditions using metallic Mg and Zn targets. We present a comprehensive study of the effects of film thickness, variation of O2 content in the working gas and annealing temperature on the structural, optical and magnetic properties. The band gap energy of the films is found to increase from 4.1 to 4.24 eV with the increase of O2 partial pressures from 5 to 20 % in the working gas. The films are found to be ferromagnetic at room temperature and the saturation magnetization increases initially with the film’s thickness reaching a maximum value of 14.6 emu/cm3 and then decreases to finally become diamagnetic beyond 95 nm thickness. Intrinsic strain seems to play an important role in the observed structural and magnetic properties of the Mg@ZnO films. On annealing, the as-obtained ‘mostly amorphous’ films in the temperature range 600 to 800°C become more crystalline and consequently the saturation magnetization values reduce., QC 20130524

Two series of Nb–Si–C thin films of different composition have been deposited using DC magnetron sputtering. In the first series the carbon content was kept at about 55 at.% while the Si/Nb ratio was varied and in the second series the C/Nb ratio was varied instead while the Si content was kept at about 45 at.%. The microstructure is strongly dependent on Si content and Nb–Si–C films containing more than 25 at.% Si exhibit an amorphous structure as determined by X-ray diffraction. Transmission electron microscopy, however, induces crystallisation during analysis, thus obstructing a more detailed analysis of the amorphous structure. X-ray photo-electron spectroscopy suggests that the amorphous films consist of a mixture of chemical bonds such as Nb–Si, Nb–C, and Si–C. The addition of Si results in a hardness decrease from 22 GPa for the binary Nb–C film to 18 – 19 GPa for the Si-containing films, while film resistivity increases from 211 μΩcm to 3215 μΩcm. Comparison with recently published results on DC magnetron sputtered Zr–Si–C films, deposited in the same system using the same Ar-plasma pressure, bias, and a slightly lower substrate temperature (300 °C instead of 350 °C), shows that hardness is primarily dependent on the amount of Si–C bonds rather than type of transition metal. The reduced elastic modulus on the other hand shows a dependency on the type of transition metal for the films. These trends for the mechanical properties suggest that high wear resistant (high H/E and H3/E2 ratio) Me–Si–C films can be achieved by appropriate choice of film composition and transition metal., Funding Agencies|Vinnova (Swedish Governmental Agency for Innovation Systems) through the VINN Excellence Centre FunMat||Swedish Research Council (VR)

We report on the effect of carbon implantation on the structural, electronic, and magnetic properties of Fe93Zr7 (FeZr) amorphous films. Extended X-ray absorption fine structure measurements on (FeZr)(100-x)C-x (x = 0, 5.5, and 11) indicate the incorporation of carbon in the FeZr matrix, with an increase of the Fe-Fe distance by implanting carbon. X-ray photoelectron spectroscopy measurements reveal the creation of Fe-C bonds after implantation. A significant enhancement of the Curie temperature and decrease of the coercivity are observed in the carbon-implanted films. Moreover, the non collinear ferromagnetism of the as-grown FeZr film diminishes upon carbon implantation.

Two series of Nb–Si–C thin films of different composition have been deposited using DC magnetron sputtering. In the first series the carbon content was kept at about 55 at.% while the Si/Nb ratio was varied and in the second series the C/Nb ratio was varied instead while the Si content was kept at about 45 at.%. The microstructure is strongly dependent on Si content and Nb–Si–C films containing more than 25 at.% Si exhibit an amorphous structure as determined by X-ray diffraction. Transmission electron microscopy, however, induces crystallisation during analysis, thus obstructing a more detailed analysis of the amorphous structure. X-ray photo-electron spectroscopy suggests that the amorphous films consist of a mixture of chemical bonds such as Nb–Si, Nb–C, and Si–C. The addition of Si results in a hardness decrease from 22 GPa for the binary Nb–C film to 18 – 19 GPa for the Si-containing films, while film resistivity increases from 211 μΩcm to 3215 μΩcm. Comparison with recently published results on DC magnetron sputtered Zr–Si–C films, deposited in the same system using the same Ar-plasma pressure, bias, and a slightly lower substrate temperature (300 °C instead of 350 °C), shows that hardness is primarily dependent on the amount of Si–C bonds rather than type of transition metal. The reduced elastic modulus on the other hand shows a dependency on the type of transition metal for the films. These trends for the mechanical properties suggest that high wear resistant (high H/E and H3/E2 ratio) Me–Si–C films can be achieved by appropriate choice of film composition and transition metal., Funding Agencies|Vinnova (Swedish Governmental Agency for Innovation Systems) through the VINN Excellence Centre FunMat||Swedish Research Council (VR)

Two series of Nb–Si–C thin films of different composition have been deposited using DC magnetron sputtering. In the first series the carbon content was kept at about 55 at.% while the Si/Nb ratio was varied and in the second series the C/Nb ratio was varied instead while the Si content was kept at about 45 at.%. The microstructure is strongly dependent on Si content and Nb–Si–C films containing more than 25 at.% Si exhibit an amorphous structure as determined by X-ray diffraction. Transmission electron microscopy, however, induces crystallisation during analysis, thus obstructing a more detailed analysis of the amorphous structure. X-ray photo-electron spectroscopy suggests that the amorphous films consist of a mixture of chemical bonds such as Nb–Si, Nb–C, and Si–C. The addition of Si results in a hardness decrease from 22 GPa for the binary Nb–C film to 18 – 19 GPa for the Si-containing films, while film resistivity increases from 211 μΩcm to 3215 μΩcm. Comparison with recently published results on DC magnetron sputtered Zr–Si–C films, deposited in the same system using the same Ar-plasma pressure, bias, and a slightly lower substrate temperature (300 °C instead of 350 °C), shows that hardness is primarily dependent on the amount of Si–C bonds rather than type of transition metal. The reduced elastic modulus on the other hand shows a dependency on the type of transition metal for the films. These trends for the mechanical properties suggest that high wear resistant (high H/E and H3/E2 ratio) Me–Si–C films can be achieved by appropriate choice of film composition and transition metal., Funding Agencies|Vinnova (Swedish Governmental Agency for Innovation Systems) through the VINN Excellence Centre FunMat||Swedish Research Council (VR)

Two series of Nb–Si–C thin films of different composition have been deposited using DC magnetron sputtering. In the first series the carbon content was kept at about 55 at.% while the Si/Nb ratio was varied and in the second series the C/Nb ratio was varied instead while the Si content was kept at about 45 at.%. The microstructure is strongly dependent on Si content and Nb–Si–C films containing more than 25 at.% Si exhibit an amorphous structure as determined by X-ray diffraction. Transmission electron microscopy, however, induces crystallisation during analysis, thus obstructing a more detailed analysis of the amorphous structure. X-ray photo-electron spectroscopy suggests that the amorphous films consist of a mixture of chemical bonds such as Nb–Si, Nb–C, and Si–C. The addition of Si results in a hardness decrease from 22 GPa for the binary Nb–C film to 18 – 19 GPa for the Si-containing films, while film resistivity increases from 211 μΩcm to 3215 μΩcm. Comparison with recently published results on DC magnetron sputtered Zr–Si–C films, deposited in the same system using the same Ar-plasma pressure, bias, and a slightly lower substrate temperature (300 °C instead of 350 °C), shows that hardness is primarily dependent on the amount of Si–C bonds rather than type of transition metal. The reduced elastic modulus on the other hand shows a dependency on the type of transition metal for the films. These trends for the mechanical properties suggest that high wear resistant (high H/E and H3/E2 ratio) Me–Si–C films can be achieved by appropriate choice of film composition and transition metal., Funding Agencies|Vinnova (Swedish Governmental Agency for Innovation Systems) through the VINN Excellence Centre FunMat||Swedish Research Council (VR)

We report on the effect of carbon implantation on the structural, electronic, and magnetic properties of Fe93Zr7 (FeZr) amorphous films. Extended X-ray absorption fine structure measurements on (FeZr)(100-x)C-x (x = 0, 5.5, and 11) indicate the incorporation of carbon in the FeZr matrix, with an increase of the Fe-Fe distance by implanting carbon. X-ray photoelectron spectroscopy measurements reveal the creation of Fe-C bonds after implantation. A significant enhancement of the Curie temperature and decrease of the coercivity are observed in the carbon-implanted films. Moreover, the non collinear ferromagnetism of the as-grown FeZr film diminishes upon carbon implantation.

Ion assisted depositions have been used to grow the Al38Cu46Sc16 quasicrystalline phase directly from the vapor phase in thin film form. Diffraction experiments reveal that amorphous films are formed at room temperature. The quasicrystalline phase formed at a substrate temperature of 340 °C with an improved quality at higher temperatures up to 460 °C. The quasicrystal film quality is improved by increasing the ion flux during ion-assisted growth with ion energies of 26.7 eV. Increasing the ion energy further was however found to cause resputtering and defects in the film. Electron microscopy reveals a polycrystalline microstructure with crystal grains in the shape of thin needles.

In this dissertation I describe measurements of dielectric loss at microwave frequencies due to two level systems (TLS) using superconducting resonators. Most measurements were performed in a dilution refrigerator at temperatures between 30 and 200 mK and all resonators discussed were fabricated with thin-film superconducting aluminum. I derive the transmission through a non-ideal (mismatched) resonant circuit and find that in general the resonance line-shape is asymmetric. I describe an analysis method for extracting the internal quality factor (Qi), the diameter correction method (DCM), and compare it to a commonly used phenomenological method, the φ rotation method (φRM). I analytically find that the φRM deterministically overestimates Qi when the asymmetry of the resonance line-shape is high. Four coplanar resonator geometries were studied, with frequencies spanning 5-7 GHz. They were all superconducting aluminum fabricated on sapphire and silicon substrates. These include a quasi-lumped element resonator, a coplanar strip transmission line resonator, and two hybrid designs that contain both a coplanar strip and a quasi-lumped element. Measured Qi's were as high as 2 × 105 for single photon excitations and there was no systematic variation in loss between quasi-lumped and coplanar strip resonance modes. I also measured the microwave loss tangent of several atomic layer deposition (ALD) grown dielectrics and obtained secondary ion mass spectrometry (SIMS) measurements of the same films. I found that hydrogen defect concentrations were correlated with low temperature microwave loss. In amorphous films that showed excess hydrogen defects on the surface, two independent TLS distributions were required to fit the loss tangent, one for the surface and one for the bulk. In crystalline dielectrics where hydrogen contamination was uniform throughout the bulk, a single bulk TLS distribution was sufficient.

The surface roughness of thin amorphous films of chalcogenide glasses (ChG) after photostimulated dissolution in amine-based selective etchant has been investigated. It is established that the rms roughness of the annealed and photoetched ChG film substantially smaller than the as-evaporated film and etched in the same selective etchant. This makes it possible to obtain more higher-quality lithographic masks or periodic relief-phase structures using new photoetching effect: photo-induced enhancement in solubility of annealed ChG layers. A possible mechanism for the photoinduced etching of ChGs is discussed. The diffraction gratings on germanium ChG - more environmentally acceptable compounds than traditionally used arsenic chalcogenides, were recorded for the first time by using the effect of hotoinduced etching on ChG layers and their characteristics were studied, Досліджено шорсткість поверхні тонких плівок аморфних халькогенідних стекол (CHG) після фотостимульованого розчинення в селективних травниках на основі амінів. Встановлено, що середньоквадратична шорсткість поверхні відпаленої та фототравленої ChG-плівки значно менша, ніж осадженої і травленої в тому ж селективному травнику плівки. Використання нового ефекту фототравлення – фотоіндукованого підвищення розчинності відпалених ChG шарів – дає можливість отримати літографічні маски або періодичні рельєфно-фазові структури вищої якості. Обговорюється можливий механізм фотоіндукованого травлення CHG-плівок. Вперше записані з використанням ефекту фотоіндукованого травлення дифракційні гратки на германієвих CHG, екологічно прийнятніші сполук, ніж традиційно використовуваних халькогенідів миш'яку; вивчено їх характеристики., Исследована шероховатость поверхности тонких пленок аморфных халькогенидных стекол (CHG) после фотостимулированного растворения в селективных травителях на основе аминов. Установлено, что среднеквадратичная шероховатость поверхности отожженной и фототравленой ChG-пленки значительно меньше, чем осажденной и травленной в том же селективном травителе пленки. Использование нового эффекта фототравления - фотоиндуцированного повышения растворимости отожженных ChG слоев - дает возможность получить литографические маски или периодические рельефно-фазовые структуры высшего качества. Обсуждается возможный механизм фотоиндуцированного травления CHG-пленок. Впервые записаны с использованием эффекта фотоиндуцированного травления дифракционные решетки на германиевых CHG, экологически более приемлемом соединении, чем традиционно используемых халькогенидов мышьяка; изучены их характеристики.

To determine the origin of the quasi-two-dimensional electron gas formed at the interface between the two complex oxides of LaAlO3 (LAO) and SrTiO3 (STO), various amorphous films of LAO, La2O3, Al2O3, and La7/8Sr1/8MnO3 (LSMO), were deposited on TiO2-terminated (0 0 1) STO substrates by pulsed laser deposition at room temperature. Metallic interfaces are observed when the over-layers are amorphous LAO, La2O3, or Al2O3, while insulating interfaces are observed when the over-layer is LSMO. The interfacial conductivity of these SrTiO3-based hetero-structures shows strong dependence on both film thickness and oxygen pressure during film growth. The possible origin for the occurrence of metallic interfaces in these complex oxide hetero-structures due to redox reactions at the STO substrate surface is discussed. A thermodynamic criterion for designing either metallic or insulating interfaces between complex oxides is proposed.

Atomic Layer Deposition (ALD) is a thin film deposition technique that has received a lot of attention in many fields of science and industry due to its sequential, self-limiting reactions. Although it is slow method, it allows uniform, high density films with conformal depositions on 3D high aspect ratio structures. ALD allows thickness control of the film down to sub nanometre range. For more understanding and future applications, certain properties like accurate thickness, density and roughness of film is needed to get characterized. In this work ALD deposited aluminium oxide, titanium dioxide, aluminium nitride and a nanolaminate sample are characterized by X-ray Diffraction (XRD), X-ray Reflectivity (XRR) and Atomic Force Microscopy (AFM) methods. The density, thickness and roughness of films are measured by XRR method. Grazing Incidence X-ray Diffraction (GIXRD) is used to examine the crystal nature of the deposited films. There were no peaks found for the amorphous films. The crystallite size and phases of crystalline films are determined by this method. AFM technique was used to see the morphology of the films. AFM gives the roughness of the films as well which was giving quiet similar results to that of roughness values found by XRR. These results give a better understanding of ALD films deposited at different temperature conditions and with different thickness values.

Photoinduced SO2 fixation on anatase TiO2 films was studied by in situ Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). The TiO2 films were prepared by reactive DC magnetron sputtering and were subsequently exposed to 50 ppm SO2 gas mixed in synthetic air and irradiated with UV light at substrate temperatures between 298 and 673 K. Simultaneous UV irradiation and SO2 exposure between 373 and 523 K resulted in significant sulfur (S) deposits on crystalline TiO2 films as determined by XPS, whereas amorphous films contained negligible amounts of S. At substrate temperatures above 523 K, the S deposits readily desorbed from TiO2. The oxidation state of sulfur successively changed from S4+ for SO2 adsorbed on crystalline TiO2 films at room temperature without irradiation to S6+ for films exposed to SO2 at elevated temperatures with simultaneous irradiation. In situ FTIR was used to monitor the temporal evolution of the photoinduced surface reaction products formed on the TiO2 surfaces. It is shown that band gap excitation of TiO2 results in photoinduced oxidation of SO2, which at elevated temperatures become coordinated to the TiO2 lattice through interactions with O vacancies and form sulfite and sulfate surface species. These species makes the surface acidic, which is manifested in nondetectable adherence of stearic acid to the modified surface. The modified films show good chemical stability as evidenced by sonication and repeated recycling of the films. The results suggest a new method to functionalize wide band gap oxide surfaces by means of photoinduced reactions in reactive gases at elevated substrate temperatures. In the case of anatase TiO2 in reactive SO2 gas, we here show that such functionalization yields surfaces with excellent oleophobic properties, as probed by adhesion of stearic acid.

Thin films in the Cr-C system with carbon content of 25-85 at.% have been deposited using non-reactive DC magnetron sputtering from elemental targets. Analyses with X-ray diffraction and transmission electron microscopy confirm that the films are completely amorphous. Also, annealing experiment show that the films had not crystallized at 500 degrees C. Furthermore, X-ray spectroscopy and Raman spectroscopy show that the films consist of two phases, an amorphous CrCx phase and an amorphous carbon (a-C) phase. The presence of two amorphous phases is also supported by the electrochemical analysis, which shows that oxidation of both chromium and carbon contributes to the total current in the passive region. The relative amounts of these amorphous phases influence the film properties. Typically, lower carbon content with less a-C phase leads to harder films with higher Young's modulus and lower resistivity. The results also show that both films have lower currents in the passive region compared to the uncoated 316L steel substrate. Finally, our results were compared with literature data from both reactively and non-reactively sputtered chromium carbide films. The comparison reveals that non-reactive sputtering tend to favour the formation of amorphous films and also influence e.g. the sp(2)/sp(3) ratio of the a-C phase.

In the Current Study, the Structural Characteristics of Siox Thin Films Grown by Magnetron Sputtering on Si Substrates Are Reported. High Resolution Transmission Electron Microscopy Revealed the Formation of Amorphous Siox Films for the as-Deposited Samples, as Well as the Ones Annealed in Ambient Air for 30 Min at 950oC and of Si Nanocrystals, Embedded in Amorphous Siox, after Ar Annealing for 1-4 Hours at 1000oC. the Nanocrystals, with Sizes up to 6 Nm, Predominately Exhibit {111} Lattice Planes. Energy-Dispersive X-Ray Analysis Showed that the Si/O Ratio Is between 0.5-1, I.e. the Amorphous Films Comprise of a Mixture of Sio2 and Sio. Phase Images and Corresponding Strain Maps Created Using Fourier Filtering Revealed a Uniform Contrast in the Nanocrystals, which Shows that the Si Lattice Constant Does Not Vary Significantly. the Residual Strain Variations, around 4%, May Account for the Possible Existence of a Small Percentage of Highly Disordered Si or Siox Residual Clusters inside the Regular Si Matrix, in Full Agreement with Photoluminescence Measurements Performed on the same Materials.

Експериментально визначені кількісні параметри контрастування електронно-цифрових зображень фазових неоднорідностей аморфних плівок As 2 S 3 . Показано, що поточний контраст має дифракційну природу і зусилля відмінності розв'язування електронів різними ділянками зразків як за пружним когерентним, так і за непружним механізмами. Основа утворення такого контрасту полягає у відсутності ближнього та проміжного порядку двох аморфних станів плівок., Экспериментально определены количественные параметры контраста на электронномикроскопических изображениях фазовых неоднородностей аморфных пленок As2S3. Показано, что данный контраст имеет дифракцион­ную природу и обусловлен отличиями рассеяния электронов разными участками образцов как по упругому когерентному, так и по неупругому механизмах. Основой формирования такого контраста являются отличия ближнего и промежуточного порядка двух аморфных состояний пленок., The quantitative parameters of the electron microscopic image contrast of phase inhomogeneous are experimentally certain for As2S3 amorphous films. It is shown that this contrast has diffraction nature and conditioned as elastic coherent so inelastic mechanisms. Basis of forming of such contrast are differences near and intermediate order two amorphous states of films.

A facile approach to thermally stable and efficient solid-state emitters is proposed. By hooking up tetraphenylethene (TPE) units through aryl linkers under Suzuki coupling conditions, a series of arylene bis(tetraphenylethene)s (TPE-Ar-TPE Ar = 2, 5-dimethyl-1, 4-phenylene, 2, 5-bis(hexyloxyl)-1, 4-phenylene, 1, 5-naphthylene, and 9, 10-anthracenylene) are prepared in satisfactory to high yields (67-96%). These molecules are nonluminescent when dissolved in solutions but become highly emissive when aggregated in poor solvents or fabricated as thin film in the solid state, displaying a phenomenon of aggregation-induced emission. Fluorescence quantum yields of 100% were achieved in the amorphous films of the luminogens. The luminogens exhibit mechano-, vapo-, and thermochromism: their emissions can be repeatedly switched between blue and blue-green colors by simple grinding-fuming and grinding-heating cycles owing to the morphological change from a crystalline to an amorphous state and vice versa. These compounds are thermally stable, losing little of their weight at high temperatures of 421-452°C. All the luminogens are morphological stable with high glass transition temperatures. Multilayer light-emitting diodes with a device configuration of ITO/NPB/dye/TPBi/Alq 3/LiF/Al are fabricated, which emit sky-blue electroluminescence with maximum luminance and external quantum efficiency of 7900 cd mr -2 and 2.1 %, respectively. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

In the thesis CuPc thin films were investigated by (in situ) SE and RAS, which are employed to determine the out-of-plane and in-plane optical anisotropy and molecular orientation, respectively. CuPc is a promising candidate of organic semiconductors used in organic field effect transistors, organic light emitting diodes and organic solar cells. Vicinal Si(111) substrates are interesting due to the in-plane anisotropy caused by the steps and terraces on the surface. The strength of in-plane anisotropy of vicinal Si(111) is dependent on the offcut angle. The influence of offcut angle on out-of-plane and in-plane molecular orientation in CuPc thin films is explored. The in situ investigation of CuPc films suggests that structural changes occur during film growth. In addition, two different surface modification layers were utilized to examine the effect on CuPc molecular orientation: OTS monolayer with upright standing molecules and PTCDA layers with flat lying molecules. Metal-organic interface plays an important role in organic electronic devices. In-CuPc is chosen to be an example system investigated employing in situ SE and RAS. When In was thermally evaporated onto CuPc film, In atoms firstly diffuse into the CuPc film underneath and then aggregate to form clusters on top. Hafnium dioxide (HfO2) is currently a hot topic to replace the conventionally used SiO2 as gate dielectrics in order to minimize leakage current when further scaling down microelectronic devices. Since HfO2 films are often crystalline, in order to obtain amorphous films which are beneficial to minimize leakage current, aluminum oxide (Al2O3) (k value: 9) which stays amorphous at much higher temperatures are combined to overcome this difficulty. Two series of ultra-thin samples were deposited by atomic layer deposition: mixed layers HfxAl1-xOz and bilayers HfO2 on Al2O3. Optical constants and bandgap are determined using SE in the energy range of 0.7-10 eV. It is found that the (effective) optica, In dieser Arbeit werden dünne Schichten aus Kupferphthalozyanin (CuPc) mittels spektroskopischer (in-situ) Ellipsometrie (SE) und (in-situ) Reflektions-Anisotropie-Spektroskopie (RAS) untersucht, um die optische Anisotropie in einer Ebene parallel und senkrecht zur Schichtoberfläche und die molekulare Orientierung zu bestimmen. CuPc ist ein aussichtsreicher Kandidat als organischer Halbleiter in organischen Feldeffekt-Transistoren, organischen Leuchtdioden und organischen Solarzellen. Vizinale Si(111)-Substrate sind wegen der Anisotropie in der Substratebene interessant, die durch die Treppen und Terrassen auf der Oberfläche verursacht wird. Die Stärke der Anisotropie der vizinalen Si(111)-Oberfläche ist vom Schnittwinkel (Offcut) abhängig. Es wird der Einfluss des Offcut-Winkels auf die molekulare Orientierung in dünnen CuPc-Schichten parallel und senkrecht zur Substratoberfläche untersucht. Die in-situ Untersuchungen von CuPc-Schichten weisen darauf hin, dass strukturelle Veränderungen beim Wachstum auftreten. Darüber hinaus wurden zwei unterschiedliche Oberflächenmodifizierungsschichten, um deren Wirkung auf die molekulare Orientierung von CuPc zu untersuchen, verwendet: eine OTS-Monoschicht mit aufrecht stehenden Molekülen und PTCDA-Schichten mit flach liegenden Molekülen. Metall-organische Grenzflächen spielen eine wichtige Rolle in organischen elektronischen Bauelementen. In-CuPc wird als Beispiel für ein Metall-organisches System durch in-situ SE und RAS untersucht. Wenn In thermisch auf eine CuPc-Schicht aufgedampft wird, diffundieren In-Atome zunächst in die darunterliegende CuPc-Schicht und bilden dann Cluster auf der Schicht. Hafniumdioxid (HfO2) ist ein heißer Kandidat für das Ersetzen des herkömmlich als Gate-Dielektrikum verwendeten SiO2 mit dem Ziel, die Leckströme bei der weiteren Verkleinerung mikroelektronischer Bauelemente zu minimieren. Um amorphe Schichten, die vorteilhaft zur Minimierung der Leckströme sind, zu erhalten, werden die HfO2-Schicht

In the thesis CuPc thin films were investigated by (in situ) SE and RAS, which are employed to determine the out-of-plane and in-plane optical anisotropy and molecular orientation, respectively. CuPc is a promising candidate of organic semiconductors used in organic field effect transistors, organic light emitting diodes and organic solar cells. Vicinal Si(111) substrates are interesting due to the in-plane anisotropy caused by the steps and terraces on the surface. The strength of in-plane anisotropy of vicinal Si(111) is dependent on the offcut angle. The influence of offcut angle on out-of-plane and in-plane molecular orientation in CuPc thin films is explored. The in situ investigation of CuPc films suggests that structural changes occur during film growth. In addition, two different surface modification layers were utilized to examine the effect on CuPc molecular orientation: OTS monolayer with upright standing molecules and PTCDA layers with flat lying molecules. Metal-organic interface plays an important role in organic electronic devices. In-CuPc is chosen to be an example system investigated employing in situ SE and RAS. When In was thermally evaporated onto CuPc film, In atoms firstly diffuse into the CuPc film underneath and then aggregate to form clusters on top. Hafnium dioxide (HfO2) is currently a hot topic to replace the conventionally used SiO2 as gate dielectrics in order to minimize leakage current when further scaling down microelectronic devices. Since HfO2 films are often crystalline, in order to obtain amorphous films which are beneficial to minimize leakage current, aluminum oxide (Al2O3) (k value: 9) which stays amorphous at much higher temperatures are combined to overcome this difficulty. Two series of ultra-thin samples were deposited by atomic layer deposition: mixed layers HfxAl1-xOz and bilayers HfO2 on Al2O3. Optical constants and bandgap are determined using SE in the energy range of 0.7-10 eV. It is found that the (effective) optica, In dieser Arbeit werden dünne Schichten aus Kupferphthalozyanin (CuPc) mittels spektroskopischer (in-situ) Ellipsometrie (SE) und (in-situ) Reflektions-Anisotropie-Spektroskopie (RAS) untersucht, um die optische Anisotropie in einer Ebene parallel und senkrecht zur Schichtoberfläche und die molekulare Orientierung zu bestimmen. CuPc ist ein aussichtsreicher Kandidat als organischer Halbleiter in organischen Feldeffekt-Transistoren, organischen Leuchtdioden und organischen Solarzellen. Vizinale Si(111)-Substrate sind wegen der Anisotropie in der Substratebene interessant, die durch die Treppen und Terrassen auf der Oberfläche verursacht wird. Die Stärke der Anisotropie der vizinalen Si(111)-Oberfläche ist vom Schnittwinkel (Offcut) abhängig. Es wird der Einfluss des Offcut-Winkels auf die molekulare Orientierung in dünnen CuPc-Schichten parallel und senkrecht zur Substratoberfläche untersucht. Die in-situ Untersuchungen von CuPc-Schichten weisen darauf hin, dass strukturelle Veränderungen beim Wachstum auftreten. Darüber hinaus wurden zwei unterschiedliche Oberflächenmodifizierungsschichten, um deren Wirkung auf die molekulare Orientierung von CuPc zu untersuchen, verwendet: eine OTS-Monoschicht mit aufrecht stehenden Molekülen und PTCDA-Schichten mit flach liegenden Molekülen. Metall-organische Grenzflächen spielen eine wichtige Rolle in organischen elektronischen Bauelementen. In-CuPc wird als Beispiel für ein Metall-organisches System durch in-situ SE und RAS untersucht. Wenn In thermisch auf eine CuPc-Schicht aufgedampft wird, diffundieren In-Atome zunächst in die darunterliegende CuPc-Schicht und bilden dann Cluster auf der Schicht. Hafniumdioxid (HfO2) ist ein heißer Kandidat für das Ersetzen des herkömmlich als Gate-Dielektrikum verwendeten SiO2 mit dem Ziel, die Leckströme bei der weiteren Verkleinerung mikroelektronischer Bauelemente zu minimieren. Um amorphe Schichten, die vorteilhaft zur Minimierung der Leckströme sind, zu erhalten, werden die HfO2-Schicht

Among amorphous films of rare earth-transition metal (RE-TM) alloys as exchange-biasing layers in magnetoresistive heads and spin-valve sensors, the amorphous Tb-Co films have most high practical potential. In the present work the influence of the temperature and the heat treatment parameters on the structure and magnetic properties was studied for exchange bias FeNi/Tb 35Co 65 bilayers annealed in vacuum or a nitrogen flow. A simple explanation of the dependence of the magnetic properties on the temperature and the heat treatment parameters connected with structural changes in each one of the layers was proposed. Copyright © 2012 American Scientific Publishers All rights reserved.

Most modern semiconductor devices, for example field-effect transistors, memory devices, and wafer-based solar cells, rely on silicon as the principle semiconductor material. Typical semiconductor devices are built-up from various functional materials with the leading dimensions on the nano- and micrometer scale. In recent years, there is a trend of introducing new materials in various fields of silicon-based semiconductor technology which holds in particular for the dielectric thin films employed. This inherently changes the interface and material properties which may impact the performance of the semiconductor devices. Three common aspects related to dielectric thin films that affect device performance are the trapping of charges in dielectric films, the creation of defects at the silicon-film interface, and the formation of (SiO2) interlayers between the film and the silicon. A fundamental insight into the interface and material properties allows for optimizing device performance and may ultimately lead to better control of the material properties such that the device functionalities can be tailored to order. This dissertation concerns the development and the use of the nonlinear optical technique of second-harmonic generation (SHG) to obtain a fundamental insight into the interface and material properties of dielectric-thin-film systems on silicon. SHG is an excellent candidate for this because of its interface specificity for centrosymmetric materials, such as crystalline silicon and amorphous films, and its sensitivity to internal electric fields. The research focuses on technologically relevant topics with the rationale to improve the functionality and performance of semiconductor devices through in-depth understanding. Specifically, the merits and opportunities of SHG spectroscopy in the vicinity of the E1 and E2 critical points of bulk silicon are addressed. Because the measured SH intensity spectra are composed of contributions related to both the silicon

Nitrogenated carbon nanotips (NCNTPs) have been synthesized using customized plasma-enhanced hot filament chemical vapor deposition. The morphological, structural, and photoluminescent properties of the NCNTPs are investigated using scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and photoluminescence spectroscopy. The photoluminescence measurements show that the NCNTPs predominantly emit a green band at room temperature while strong blue emission is generated at 77 K. It is shown that these very different emission behaviors are related to the change of the optical band-gap and the concentration of the paramagnetic defects of the carbon nanotips. The studies shed light on the controversies on the photoluminescence mechanisms of carbon-based amorphous films measured at different temperatures. The relevance of the results to the use of nitrogenated carbon nanotips in light-emitting optoelectronic devices is discussed.

In the thesis CuPc thin films were investigated by (in situ) SE and RAS, which are employed to determine the out-of-plane and in-plane optical anisotropy and molecular orientation, respectively. CuPc is a promising candidate of organic semiconductors used in organic field effect transistors, organic light emitting diodes and organic solar cells. Vicinal Si(111) substrates are interesting due to the in-plane anisotropy caused by the steps and terraces on the surface. The strength of in-plane anisotropy of vicinal Si(111) is dependent on the offcut angle. The influence of offcut angle on out-of-plane and in-plane molecular orientation in CuPc thin films is explored. The in situ investigation of CuPc films suggests that structural changes occur during film growth. In addition, two different surface modification layers were utilized to examine the effect on CuPc molecular orientation: OTS monolayer with upright standing molecules and PTCDA layers with flat lying molecules. Metal-organic interface plays an important role in organic electronic devices. In-CuPc is chosen to be an example system investigated employing in situ SE and RAS. When In was thermally evaporated onto CuPc film, In atoms firstly diffuse into the CuPc film underneath and then aggregate to form clusters on top. Hafnium dioxide (HfO2) is currently a hot topic to replace the conventionally used SiO2 as gate dielectrics in order to minimize leakage current when further scaling down microelectronic devices. Since HfO2 films are often crystalline, in order to obtain amorphous films which are beneficial to minimize leakage current, aluminum oxide (Al2O3) (k value: 9) which stays amorphous at much higher temperatures are combined to overcome this difficulty. Two series of ultra-thin samples were deposited by atomic layer deposition: mixed layers HfxAl1-xOz and bilayers HfO2 on Al2O3. Optical constants and bandgap are determined using SE in the energy range of 0.7-10 eV. It is found that the (effective) optica, In dieser Arbeit werden dünne Schichten aus Kupferphthalozyanin (CuPc) mittels spektroskopischer (in-situ) Ellipsometrie (SE) und (in-situ) Reflektions-Anisotropie-Spektroskopie (RAS) untersucht, um die optische Anisotropie in einer Ebene parallel und senkrecht zur Schichtoberfläche und die molekulare Orientierung zu bestimmen. CuPc ist ein aussichtsreicher Kandidat als organischer Halbleiter in organischen Feldeffekt-Transistoren, organischen Leuchtdioden und organischen Solarzellen. Vizinale Si(111)-Substrate sind wegen der Anisotropie in der Substratebene interessant, die durch die Treppen und Terrassen auf der Oberfläche verursacht wird. Die Stärke der Anisotropie der vizinalen Si(111)-Oberfläche ist vom Schnittwinkel (Offcut) abhängig. Es wird der Einfluss des Offcut-Winkels auf die molekulare Orientierung in dünnen CuPc-Schichten parallel und senkrecht zur Substratoberfläche untersucht. Die in-situ Untersuchungen von CuPc-Schichten weisen darauf hin, dass strukturelle Veränderungen beim Wachstum auftreten. Darüber hinaus wurden zwei unterschiedliche Oberflächenmodifizierungsschichten, um deren Wirkung auf die molekulare Orientierung von CuPc zu untersuchen, verwendet: eine OTS-Monoschicht mit aufrecht stehenden Molekülen und PTCDA-Schichten mit flach liegenden Molekülen. Metall-organische Grenzflächen spielen eine wichtige Rolle in organischen elektronischen Bauelementen. In-CuPc wird als Beispiel für ein Metall-organisches System durch in-situ SE und RAS untersucht. Wenn In thermisch auf eine CuPc-Schicht aufgedampft wird, diffundieren In-Atome zunächst in die darunterliegende CuPc-Schicht und bilden dann Cluster auf der Schicht. Hafniumdioxid (HfO2) ist ein heißer Kandidat für das Ersetzen des herkömmlich als Gate-Dielektrikum verwendeten SiO2 mit dem Ziel, die Leckströme bei der weiteren Verkleinerung mikroelektronischer Bauelemente zu minimieren. Um amorphe Schichten, die vorteilhaft zur Minimierung der Leckströme sind, zu erhalten, werden die HfO2-Schicht

Transparent conductive oxides (TCO), mainly In2O3:Sn (ITO), ZnO:Al (AZO) and SnO2:F (FTO) are widely used as transparent electrodes in flat panel displays, thin film solar cells and solid state lighting. The markets for the applications requiring large area electrodes are continuously growing recent years which drives the need for a cost-efficient replacement of conventional TCOs. In addition to a low cost, TiO2 offers unique combination of high refractive index, stability against humidity, the high chemical stability and the non-toxicity. The Nb or Ta doped TiO2 films epitaxially grown on crystalline substrates show electrical and optical properties which are comparable to those of conventional TCOs. However, using expensive crystalline substrates drastically limits applications. It is still a challenge to achieve low electrical resistivity polycrystalline TiO2 films as required for the most applications. Furthermore, it is not possible to get low resistivity in polycrystalline films by direct growth at elevated substrate temperature. Only a two-step approach containing the deposition of amorphous films followed by annealing in vacuum or hydrogen delivers films with resistivity values in the range of 1·10-3 cm. Even in that case, it is known that electrical, optical and structural properties evolution during crystallization, and crystallization itself, is strongly affected by the Ti/O ratio in the as-deposited films. Achieving required Ti/O ratio remains the main challenge. In order to address this problem, we studied the films formed on glass substrates without heating by DC magnetron sputtering of reduced TiO2-x:Ta ceramic targets followed by vacuum annealing. We achieved oxygen fine-tuning using a MS process in conjunction with a plasma feedback system. The optimum total pressure in combination with O2 fine tuning yielded the films with the best free electron mobility of 8 cm²/Vs. Our approach delivered films with an electrical resistivity in the range of 10-3 W

Transparent conductive oxides (TCO), mainly In2O3:Sn (ITO), ZnO:Al (AZO) and SnO2:F (FTO) are widely used as transparent electrodes in flat panel displays, thin film solar cells and solid state lighting. The markets for the applications requiring large area electrodes are continuously growing recent years which drives the need for a cost-efficient replacement of conventional TCOs. In addition to a low cost, TiO2 offers unique combination of high refractive index, stability against humidity, the high chemical stability and the non-toxicity. The Nb or Ta doped TiO2 films epitaxially grown on crystalline substrates show electrical and optical properties which are comparable to those of conventional TCOs. However, using expensive crystalline substrates drastically limits applications. It is still a challenge to achieve low electrical resistivity polycrystalline TiO2 films as required for the most applications. Furthermore, it is not possible to get low resistivity in polycrystalline films by direct growth at elevated substrate temperature. Only a two-step approach containing the deposition of amorphous films followed by annealing in vacuum or hydrogen delivers films with resistivity values in the range of 1·10-3 cm. Even in that case, it is known that electrical, optical and structural properties evolution during crystallization, and crystallization itself, is strongly affected by the Ti/O ratio in the as-deposited films. Achieving required Ti/O ratio remains the main challenge. In order to address this problem, we studied the films formed on glass substrates without heating by DC magnetron sputtering of reduced TiO2-x:Ta ceramic targets followed by vacuum annealing. We achieved oxygen fine-tuning using a MS process in conjunction with a plasma feedback system. The optimum total pressure in combination with O2 fine tuning yielded the films with the best free electron mobility of 8 cm²/Vs. Our approach delivered films with an electrical resistivity in the range of 10-3 W

Lithium silicate thin films, which are interesting materials for example in lithium ion batteries, were grown by the atomic layer deposition technique from lithium hexamethyldisilazide [LiHMDS, Li(N(SiMe3)2)] and ozone precursors. Films were obtained at a wide deposition temperature range between 150 and 400 °C. All the films were amorphous except at 400 °C, where partial decomposition of LiHMDS was also observed. The growth behavior was examined in detail at 250 °C, and saturation of growth rates and refractive indices with precursor doses was confirmed, thereby verifying self-limiting surface reactions. Likewise, the linear thickness dependence of the films with the number of deposition cycles was verified. Strong dependence of growth rate and film composition on deposition temperature was also seen. Overall, the amorphous films grown at 250 °C had a stoichiometry close to lithium metasilicate (Li2.0SiO2.9) with 0.7 at. % carbon and 4.6 at. % hydrogen impurities. The corresponding growth rate and refractive index (n580) were 0.8 A/cycle and about 1.55.

The atomic layer deposition (ALD) of phosphate containing thin films using reactions between metal halide and phosphorus source without any additional oxygen sources was examined. Two very common metal halides, AlCl3 and TiCl4, were used in conjunction with trimethyl phosphate (TMPO) to grow corresponding metal phosphate films. Aluminum phosphate thin films were deposited at temperatures between 150 and 400 °C while titanium phosphate films grew between 275 and 450 °C. Amorphous films of Al2.6PO7.0 and Al1.6PO5.6 were deposited at 200 and 300 °C, respectively, while the amorphous titanium phosphate films deposited at 300 and 400 °C consisted of Ti0.8PO3.9 and Ti0.6PO3.5 (Ti1.2P2O7). The films were analyzed using high temperature XRD to study the crystallization and stability of the deposited films. Also the surface morphology of the annealed films was examined by FESEM.

A facile approach to thermally stable and efficient solid-state emitters is proposed. By hooking up tetraphenylethene (TPE) units through aryl linkers under Suzuki coupling conditions, a series of arylene bis(tetraphenylethene)s (TPE-Ar-TPE Ar = 2, 5-dimethyl-1, 4-phenylene, 2, 5-bis(hexyloxyl)-1, 4-phenylene, 1, 5-naphthylene, and 9, 10-anthracenylene) are prepared in satisfactory to high yields (67-96%). These molecules are nonluminescent when dissolved in solutions but become highly emissive when aggregated in poor solvents or fabricated as thin film in the solid state, displaying a phenomenon of aggregation-induced emission. Fluorescence quantum yields of 100% were achieved in the amorphous films of the luminogens. The luminogens exhibit mechano-, vapo-, and thermochromism: their emissions can be repeatedly switched between blue and blue-green colors by simple grinding-fuming and grinding-heating cycles owing to the morphological change from a crystalline to an amorphous state and vice versa. These compounds are thermally stable, losing little of their weight at high temperatures of 421-452°C. All the luminogens are morphological stable with high glass transition temperatures. Multilayer light-emitting diodes with a device configuration of ITO/NPB/dye/TPBi/Alq 3/LiF/Al are fabricated, which emit sky-blue electroluminescence with maximum luminance and external quantum efficiency of 7900 cd mr -2 and 2.1 %, respectively. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Most modern semiconductor devices, for example field-effect transistors, memory devices, and wafer-based solar cells, rely on silicon as the principle semiconductor material. Typical semiconductor devices are built-up from various functional materials with the leading dimensions on the nano- and micrometer scale. In recent years, there is a trend of introducing new materials in various fields of silicon-based semiconductor technology which holds in particular for the dielectric thin films employed. This inherently changes the interface and material properties which may impact the performance of the semiconductor devices. Three common aspects related to dielectric thin films that affect device performance are the trapping of charges in dielectric films, the creation of defects at the silicon-film interface, and the formation of (SiO2) interlayers between the film and the silicon. A fundamental insight into the interface and material properties allows for optimizing device performance and may ultimately lead to better control of the material properties such that the device functionalities can be tailored to order. This dissertation concerns the development and the use of the nonlinear optical technique of second-harmonic generation (SHG) to obtain a fundamental insight into the interface and material properties of dielectric-thin-film systems on silicon. SHG is an excellent candidate for this because of its interface specificity for centrosymmetric materials, such as crystalline silicon and amorphous films, and its sensitivity to internal electric fields. The research focuses on technologically relevant topics with the rationale to improve the functionality and performance of semiconductor devices through in-depth understanding. Specifically, the merits and opportunities of SHG spectroscopy in the vicinity of the E1 and E2 critical points of bulk silicon are addressed. Because the measured SH intensity spectra are composed of contributions related to both the silicon

In the thesis CuPc thin films were investigated by (in situ) SE and RAS, which are employed to determine the out-of-plane and in-plane optical anisotropy and molecular orientation, respectively. CuPc is a promising candidate of organic semiconductors used in organic field effect transistors, organic light emitting diodes and organic solar cells. Vicinal Si(111) substrates are interesting due to the in-plane anisotropy caused by the steps and terraces on the surface. The strength of in-plane anisotropy of vicinal Si(111) is dependent on the offcut angle. The influence of offcut angle on out-of-plane and in-plane molecular orientation in CuPc thin films is explored. The in situ investigation of CuPc films suggests that structural changes occur during film growth. In addition, two different surface modification layers were utilized to examine the effect on CuPc molecular orientation: OTS monolayer with upright standing molecules and PTCDA layers with flat lying molecules. Metal-organic interface plays an important role in organic electronic devices. In-CuPc is chosen to be an example system investigated employing in situ SE and RAS. When In was thermally evaporated onto CuPc film, In atoms firstly diffuse into the CuPc film underneath and then aggregate to form clusters on top. Hafnium dioxide (HfO2) is currently a hot topic to replace the conventionally used SiO2 as gate dielectrics in order to minimize leakage current when further scaling down microelectronic devices. Since HfO2 films are often crystalline, in order to obtain amorphous films which are beneficial to minimize leakage current, aluminum oxide (Al2O3) (k value: 9) which stays amorphous at much higher temperatures are combined to overcome this difficulty. Two series of ultra-thin samples were deposited by atomic layer deposition: mixed layers HfxAl1-xOz and bilayers HfO2 on Al2O3. Optical constants and bandgap are determined using SE in the energy range of 0.7-10 eV. It is found that the (effective) optica, In dieser Arbeit werden dünne Schichten aus Kupferphthalozyanin (CuPc) mittels spektroskopischer (in-situ) Ellipsometrie (SE) und (in-situ) Reflektions-Anisotropie-Spektroskopie (RAS) untersucht, um die optische Anisotropie in einer Ebene parallel und senkrecht zur Schichtoberfläche und die molekulare Orientierung zu bestimmen. CuPc ist ein aussichtsreicher Kandidat als organischer Halbleiter in organischen Feldeffekt-Transistoren, organischen Leuchtdioden und organischen Solarzellen. Vizinale Si(111)-Substrate sind wegen der Anisotropie in der Substratebene interessant, die durch die Treppen und Terrassen auf der Oberfläche verursacht wird. Die Stärke der Anisotropie der vizinalen Si(111)-Oberfläche ist vom Schnittwinkel (Offcut) abhängig. Es wird der Einfluss des Offcut-Winkels auf die molekulare Orientierung in dünnen CuPc-Schichten parallel und senkrecht zur Substratoberfläche untersucht. Die in-situ Untersuchungen von CuPc-Schichten weisen darauf hin, dass strukturelle Veränderungen beim Wachstum auftreten. Darüber hinaus wurden zwei unterschiedliche Oberflächenmodifizierungsschichten, um deren Wirkung auf die molekulare Orientierung von CuPc zu untersuchen, verwendet: eine OTS-Monoschicht mit aufrecht stehenden Molekülen und PTCDA-Schichten mit flach liegenden Molekülen. Metall-organische Grenzflächen spielen eine wichtige Rolle in organischen elektronischen Bauelementen. In-CuPc wird als Beispiel für ein Metall-organisches System durch in-situ SE und RAS untersucht. Wenn In thermisch auf eine CuPc-Schicht aufgedampft wird, diffundieren In-Atome zunächst in die darunterliegende CuPc-Schicht und bilden dann Cluster auf der Schicht. Hafniumdioxid (HfO2) ist ein heißer Kandidat für das Ersetzen des herkömmlich als Gate-Dielektrikum verwendeten SiO2 mit dem Ziel, die Leckströme bei der weiteren Verkleinerung mikroelektronischer Bauelemente zu minimieren. Um amorphe Schichten, die vorteilhaft zur Minimierung der Leckströme sind, zu erhalten, werden die HfO2-Schicht

To determine the origin of the quasi-two-dimensional electron gas formed at the interface between the two complex oxides of LaAlO3 (LAO) and SrTiO3 (STO), various amorphous films of LAO, La2O3, Al2O3, and La7/8Sr1/8MnO3 (LSMO), were deposited on TiO2-terminated (0 0 1) STO substrates by pulsed laser deposition at room temperature. Metallic interfaces are observed when the over-layers are amorphous LAO, La2O3, or Al2O3, while insulating interfaces are observed when the over-layer is LSMO. The interfacial conductivity of these SrTiO3-based hetero-structures shows strong dependence on both film thickness and oxygen pressure during film growth. The possible origin for the occurrence of metallic interfaces in these complex oxide hetero-structures due to redox reactions at the STO substrate surface is discussed. A thermodynamic criterion for designing either metallic or insulating interfaces between complex oxides is proposed.

[EN] The multifunctionality in ferroelectric materials makes them very useful in applications such as non-volatile memories, infrared sensors or microelectromechanical systems. The constant evolution of the electronic devices towards miniaturization requires the integration of the ferroelectric in the Si-technology, and therefore, its manufacture as a thin film onto a semiconductor substrate. The formation of the crystalline phase, responsible for the ferroelectric response, requires high temperatures (up to 600°C). This is a problem when integrating the ferroelectric in the semiconductor circuit, since these devices are not capable of withstanding temperatures over 500°C without degradation. In addition, further investigations are currently being carried out focused on the use of new flexible polymeric substrates, which requires working at temperatures below 450°C. This is the reason why new strategies are investigated to reduce the processing temperature of functional oxide films. This work has successfully used a method called Photo-Chemical Solution Deposition (PCSD) as a way to reduce the processing temperature of thin films. This method involves applying UV irradiation of the amorphous films deposited from the precursor solutions in order to promote crystallization of the ferroelectric oxide at low temperature, what requires that such solutions are capable of absorbing UV light. In this thesis ferroelectric thin films of lead titanate (PbTiO3, PT) have been prepared at only 400°C by PCSD designing a new synthesis strategy of the precursor solutions, and characterized from a structural, microstructural and electrical point of view. The fabrication of the films has been carried out by spin-coating the solutions onto Pt/TiO2/SiO2/Si(100) substrates, followed by drying and thermal treatment in a Rapid Thermal Processing oven combined with UV irradiation for the removal of organics and the low temperature crystallization of the oxide. The addition of N-methyldietha, [ES] La multifuncionalidad de los materiales ferroeléctricos los hace muy útiles en aplicaciones tales como memorias no volátiles, sensores de infrarrojos o sistemas microelectromecánicos. La constante evolución de los dispositivos electrónicos hacia la miniaturización requiere la integración del ferroeléctrico en la tecnología del silicio, y por lo tanto, su fabricación como una película delgada sobre un substrato semiconductor. La formación de la fase cristalina, responsable de la ferroelectricidad, requiere temperaturas elevadas (de hasta 600 °C). Esto es un problema cuando se integra el ferroeléctrico en el circuito semiconductor, puesto que estos dispositivos no son capaces de resistir temperaturas superiores a 500 °C sin degradarse. Además, se están llevando a cabo nuevas investigaciones centradas en la utilización de nuevos substratos poliméricos flexibles, lo que requiere trabajar a temperaturas por debajo de 450 °C. Esta es la razón por la que se investigan nuevas estrategias para reducir la temperatura de procesado de películas de óxido funcionales. Este trabajo ha utilizado con éxito un método denominado depósito foto-químico de disoluciones (PCSD) como una forma de reducir la temperatura de procesado de las películas delgadas. Este método implica la irradiación de luz UV sobre las películas amorfas depositadas a partir de las disoluciones precursoras con el fin de promover la cristalización del óxido ferroeléctrico a baja temperatura, lo que exige que tales disoluciones sean capaces de absorber la luz UV. En esta tesis se han preparado láminas delgadas ferroeléctricas de titanato de plomo (PbTiO3, PT) a tan sólo 400 °C mediante PCSD diseñando una nueva estrategia de síntesis de las disoluciones precursoras, y se han caracterizado desde un punto de vista estructural, microestructural y eléctrico. La fabricación de las películas se ha llevado a cabo mediante recubrimiento por rotación de las disoluciones sobre substratos Pt/TiO2/SiO2 / Si(100), seguido del

To determine the origin of the quasi-two-dimensional electron gas formed at the interface between the two complex oxides of LaAlO3 (LAO) and SrTiO3 (STO), various amorphous films of LAO, La2O3, Al2O3, and La7/8Sr1/8MnO3 (LSMO), were deposited on TiO2-terminated (0 0 1) STO substrates by pulsed laser deposition at room temperature. Metallic interfaces are observed when the over-layers are amorphous LAO, La2O3, or Al2O3, while insulating interfaces are observed when the over-layer is LSMO. The interfacial conductivity of these SrTiO3-based hetero-structures shows strong dependence on both film thickness and oxygen pressure during film growth. The possible origin for the occurrence of metallic interfaces in these complex oxide hetero-structures due to redox reactions at the STO substrate surface is discussed. A thermodynamic criterion for designing either metallic or insulating interfaces between complex oxides is proposed.

The preliminary goal of achieving facility in the growth and characterization of thin amorphous silver nitride films was reached without difficulty. Thermal annealing studies resulted in the discovery of both bubble formation and crystallization in the film. This research can be divided into three segments. First is the fabrication of the amorphous films themselves. Second, the thermal stability of the films on various substrates would be investigated. Thirdly, the knowledge obtained about the structure and properties of the material would be utilized in understanding and further refining the science of thin film deposition. These divisions were reflected finally in the preparation of three publications: Near Infrared Rugate Filter Fabrication by Ion Beam Assisted Deposition of Si(1-x) N(x) Films - The major emphasis of this paper is on the optical properties of the films. Stability of Silicon Nitride Coatings Produced by Ion Assisted Deposition; Fractal and spherulitic Morphology of Silicon Nitride Crystallized from Amorphous Films.

The decoration of substrate surfaces is a simple technique for inducing growth defects in high temperature superconductor films in order to artificially introduce nanostructures as flux pinning centers, which can effectively improve the critical current density and magnetic field dependence. In this paper, we attempted to develop a novel technology of surface decoration induced second phase flux pinning centers. BaTiO3 decoration has been applied to LaAlO3 substrate surfaces by using chemical solution deposition. Different heat-treatment processes were used to anneal amorphous films, and the effects of the annealing conditions on the shape, size, and density of the BaTiO3 particles have been systematically investigated. YBa2Cu3O7 (YBCO) film with BaTiO3 second phase was deposited on the top of the decorated substrate.

The decoration of substrate surfaces is a simple technique for inducing growth defects in high temperature superconductor films in order to artificially introduce nanostructures as flux pinning centers, which can effectively improve the critical current density and magnetic field dependence. In this paper, we attempted to develop a novel technology of surface decoration induced second phase flux pinning centers. BaTiO3 decoration has been applied to LaAlO3 substrate surfaces by using chemical solution deposition. Different heat-treatment processes were used to anneal amorphous films, and the effects of the annealing conditions on the shape, size, and density of the BaTiO3 particles have been systematically investigated. YBa2Cu3O7 (YBCO) film with BaTiO3 second phase was deposited on the top of the decorated substrate.

We present an in situ Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) study of the photo-induced SO2 fixation on anatase TiO2 films. TiO2 films were prepared by DC magnetron sputtering and subsequently exposed to SO2 gas mixed in synthetic air. Simultaneous UV irradiation and SO2 exposure between 373 and 523 K resulted in significant SOx deposits on crystalline TiO2 films as determined by XPS, whereas amorphous films contained negligible amounts of SOx species. The oxidation state of sulfur successively changed from S4+ for SO2 adsorbed on crystalline TiO2 films at room temperature without irradiation to S6+ for films exposed to SO2 at elevated temperatures with simultaneous irradiation. With in situ FTIR the temporal evolution of the photo-induced surface reaction products formed on the TiO2 surfaces was monitored. It is shown that band gap excitation of TiO2 results in photo-induced oxidation of SO2 to form sulfite and sulfate species, which at elevated temperatures become coordinated to the TiO2 surface through interactions with O vacancies. These species makes the oxide surface acidic and is manifested in weak adherence of stearic acid. The films show good stability as evidenced by sonication, repeated stearic acid and rinsing experiments. These results suggest that photo-induced surface treatment in reactive sulfur gases may be interesting for fabrication of oleophobic and anti-greasing coatings. Moreover, the SO2 modified shows excellent properties for sustained decomposition of acetaldehyde, a common indoor air pollutant. This is shown to be due to improved resistance towards site inhibition from carboxylate fragments which otherwise is known to impede the photocatalytic activity of TiO2 in gas-phase applications. Again this is attributed to a beneficial effect of the surface acid sites originating from the surface functionalization.

This thesis discusses two different magnetic materials: epitaxial yttrium iron garnet (YIG) and heteromorphous CoFeB-SiO2 films. YIG films were grown by pulse laser deposition (PLD) techniques onto gadolinium gallium garnet (GGG) substrates of (111) and (001) crystal orientations. Using stoichiometric and overstoichiometric ablative targets, we developed two types of YIG submicron films. The films grown from overstoichiometric targets have magnetic properties slightly different from standard liquid phase epitaxy (LPE) YIGs. They also demonstrate good substrate matching and approximately 6% nonstoichiometry. In contrary, films grown from stoichiometric targets posses surprisingly high values of uniaxial anisotropy, meanwhile cubic anisotropy is reduced several times. These films also reveal strong lattice distortions and nonstoichiometry around 17%. Employing Weiss molecular field theory and single-ion anisotropy model we determined the preferential occupancy of the octahedral [a] positions in the YIG cubic lattices by Fe3+ vacancies. The vacancies were found to be preferentially oriented along the growth direction perpendicular to the film surface. We called this effect “deformation blockade”. Different magnetostatic surface wave (MSSW) filters were also demonstrated. The filters employ high uniaxial anisotropy in YIG submicron films with magnetic losses ΔH ~ 1 Oe. Heteromorphous CoFeB-SiO2 films were deposited onto glass substrates employing carrousel magnetron sputtering. This novel technique allows amorphous films fabrication with record high in-plane anisotropy. The induced anisotropy fields here are approximately dozen times greater the values achieved using conventional growth technique when external bias field is applied during deposition process. Interesting observations were made studying CoFeB-SiO2 magnetization dynamics in the wide frequency range from 500 kHz up to 15 GHz. Two different anomalies of the magnetic susceptibility were found at the field o, QC 20111122

We present an in situ Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) study of the photo-induced SO2 fixation on anatase TiO2 films. TiO2 films were prepared by DC magnetron sputtering and subsequently exposed to SO2 gas mixed in synthetic air. Simultaneous UV irradiation and SO2 exposure between 373 and 523 K resulted in significant SOx deposits on crystalline TiO2 films as determined by XPS, whereas amorphous films contained negligible amounts of SOx species. The oxidation state of sulfur successively changed from S4+ for SO2 adsorbed on crystalline TiO2 films at room temperature without irradiation to S6+ for films exposed to SO2 at elevated temperatures with simultaneous irradiation. With in situ FTIR the temporal evolution of the photo-induced surface reaction products formed on the TiO2 surfaces was monitored. It is shown that band gap excitation of TiO2 results in photo-induced oxidation of SO2 to form sulfite and sulfate species, which at elevated temperatures become coordinated to the TiO2 surface through interactions with O vacancies. These species makes the oxide surface acidic and is manifested in weak adherence of stearic acid (Fig. 1). The films show good stability as evidenced by sonication, repeated stearic acid and rinsing experiments. These results suggest that photo-induced surface treatment in reactive sulfur gases may be interesting for fabrication of oleophobic and anti-greasing coatings. Moreover, the SO2 modified shows excellent properties for sustained decomposition of acetaldehyde, a common indoor air pollutant. This is shown to be due to improved resistance towards site inhibition from carboxylate fragments which otherwise is known to impede the photocatalytic activity of TiO2 in gas-phase applications. Again this is attributed to a beneficial effect of the surface acid sites originating from the surface functionalization.

This thesis discusses two different magnetic materials: epitaxial yttrium iron garnet (YIG) and heteromorphous CoFeB-SiO2 films. YIG films were grown by pulse laser deposition (PLD) techniques onto gadolinium gallium garnet (GGG) substrates of (111) and (001) crystal orientations. Using stoichiometric and overstoichiometric ablative targets, we developed two types of YIG submicron films. The films grown from overstoichiometric targets have magnetic properties slightly different from standard liquid phase epitaxy (LPE) YIGs. They also demonstrate good substrate matching and approximately 6% nonstoichiometry. In contrary, films grown from stoichiometric targets posses surprisingly high values of uniaxial anisotropy, meanwhile cubic anisotropy is reduced several times. These films also reveal strong lattice distortions and nonstoichiometry around 17%. Employing Weiss molecular field theory and single-ion anisotropy model we determined the preferential occupancy of the octahedral [a] positions in the YIG cubic lattices by Fe3+ vacancies. The vacancies were found to be preferentially oriented along the growth direction perpendicular to the film surface. We called this effect “deformation blockade”. Different magnetostatic surface wave (MSSW) filters were also demonstrated. The filters employ high uniaxial anisotropy in YIG submicron films with magnetic losses ΔH ~ 1 Oe. Heteromorphous CoFeB-SiO2 films were deposited onto glass substrates employing carrousel magnetron sputtering. This novel technique allows amorphous films fabrication with record high in-plane anisotropy. The induced anisotropy fields here are approximately dozen times greater the values achieved using conventional growth technique when external bias field is applied during deposition process. Interesting observations were made studying CoFeB-SiO2 magnetization dynamics in the wide frequency range from 500 kHz up to 15 GHz. Two different anomalies of the magnetic susceptibility were found at the field o, QC 20111122

Amorphous carbon and amorphous, graphitic and fullerene-like carbon nitride thin filmswere deposited by reactive magnetron sputtering and optically characterized withspectroscopic ellipsometry. The films were exposed to human serum albumin and theadsorption was monitored in situ using dynamic ellipsometry. From the ellipsometric data theadsorbed amount of proteins was quantified in terms of surface mass density using de Feijter'smodel. The results indicated larger adsorption of proteins onto the amorphous films comparedto the films with a more ordered microstructure. Complementary studies with labeled HSAusing radioimmunoassay showed up to 6 times higher protein adsorption compared to theellipsometry measurement which partly might be explained by differences in surfaceroughness (from 0.3 to 13 nm) among the films. The elutability of adsorbed labeled HSAusing unlabeled HSA and sodium dodecyl sulphate was low compared to a silicon reference.In addition, the four types of films were incubated in blood plasma followed by antifibrinogen,anti-HMWK or anti-C3c revealing the materials response to complement andcontact activation. Three of the films indicated immunoactivity, whereas the amorphouscarbon showed less immunoactivity compared to a titanium reference. All films showedindications of a stronger ability to initiate the intrinsic pathway of coagulation, compared tothe reference. Finally, the surfaces bone bonding ability was investigated by examination oftheir ability to form calcium phosphate (CaP) crystals in a simulated body fluid, with a-CNxdepositing most CaP after 21 days of incubation., Original Publication:Torun Berlind, Pentti Tengvall, Lars Hultman and Hans Arwin, Protein adsorption on thin films of carbon and carbon nitride monitored with in situ ellipsometry, 2011, ACTA BIOMATERIALIA, (7), 3, 1369-1378.http://dx.doi.org/10.1016/j.actbio.2010.10.024Copyright: Elsevier Science B.V. Amsterdamhttp://www.elsevier.com

Amorphous carbon and amorphous, graphitic and fullerene-like carbon nitride thin filmswere deposited by reactive magnetron sputtering and optically characterized withspectroscopic ellipsometry. The films were exposed to human serum albumin and theadsorption was monitored in situ using dynamic ellipsometry. From the ellipsometric data theadsorbed amount of proteins was quantified in terms of surface mass density using de Feijter'smodel. The results indicated larger adsorption of proteins onto the amorphous films comparedto the films with a more ordered microstructure. Complementary studies with labeled HSAusing radioimmunoassay showed up to 6 times higher protein adsorption compared to theellipsometry measurement which partly might be explained by differences in surfaceroughness (from 0.3 to 13 nm) among the films. The elutability of adsorbed labeled HSAusing unlabeled HSA and sodium dodecyl sulphate was low compared to a silicon reference.In addition, the four types of films were incubated in blood plasma followed by antifibrinogen,anti-HMWK or anti-C3c revealing the materials response to complement andcontact activation. Three of the films indicated immunoactivity, whereas the amorphouscarbon showed less immunoactivity compared to a titanium reference. All films showedindications of a stronger ability to initiate the intrinsic pathway of coagulation, compared tothe reference. Finally, the surfaces bone bonding ability was investigated by examination oftheir ability to form calcium phosphate (CaP) crystals in a simulated body fluid, with a-CNxdepositing most CaP after 21 days of incubation., Original Publication:Torun Berlind, Pentti Tengvall, Lars Hultman and Hans Arwin, Protein adsorption on thin films of carbon and carbon nitride monitored with in situ ellipsometry, 2011, ACTA BIOMATERIALIA, (7), 3, 1369-1378.http://dx.doi.org/10.1016/j.actbio.2010.10.024Copyright: Elsevier Science B.V. Amsterdamhttp://www.elsevier.com

This thesis discusses two different magnetic materials: epitaxial yttrium iron garnet (YIG) and heteromorphous CoFeB-SiO2 films. YIG films were grown by pulse laser deposition (PLD) techniques onto gadolinium gallium garnet (GGG) substrates of (111) and (001) crystal orientations. Using stoichiometric and overstoichiometric ablative targets, we developed two types of YIG submicron films. The films grown from overstoichiometric targets have magnetic properties slightly different from standard liquid phase epitaxy (LPE) YIGs. They also demonstrate good substrate matching and approximately 6% nonstoichiometry. In contrary, films grown from stoichiometric targets posses surprisingly high values of uniaxial anisotropy, meanwhile cubic anisotropy is reduced several times. These films also reveal strong lattice distortions and nonstoichiometry around 17%. Employing Weiss molecular field theory and single-ion anisotropy model we determined the preferential occupancy of the octahedral [a] positions in the YIG cubic lattices by Fe3+ vacancies. The vacancies were found to be preferentially oriented along the growth direction perpendicular to the film surface. We called this effect “deformation blockade”. Different magnetostatic surface wave (MSSW) filters were also demonstrated. The filters employ high uniaxial anisotropy in YIG submicron films with magnetic losses ΔH ~ 1 Oe. Heteromorphous CoFeB-SiO2 films were deposited onto glass substrates employing carrousel magnetron sputtering. This novel technique allows amorphous films fabrication with record high in-plane anisotropy. The induced anisotropy fields here are approximately dozen times greater the values achieved using conventional growth technique when external bias field is applied during deposition process. Interesting observations were made studying CoFeB-SiO2 magnetization dynamics in the wide frequency range from 500 kHz up to 15 GHz. Two different anomalies of the magnetic susceptibility were found at the field o, QC 20111122

Hafnium oxide gate dielectrics doped with a one to two percent of aluminum are grown on In0.53Ga0.47As channels by codeposition of trimethylaluminum TMA and hafnium tertbutoxide HTB. It is shown that the addition of TMA during growth allows for smooth, amorphous films that can be scaled to 5 nm physical thickness. Metal-oxide-semiconductor capacitors MOSCAPs with this dielectric have an equivalent oxide thickness of 1 nm, show an unpinned, efficient Fermi level movement and lower interface trap densities than MOSCAPs with HfO2 dielectrics grown by sequential TMA/HTB deposition.