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Homologous series are layered phases that can have a range of stoichiometries depending on an index n. Examples of perovskite-related homologous series include (ABO3)nAO Ruddlesden–Popper phases and (Bi2O2) (An−1BnO3n+1) Aurivillius phases. It is challenging to precisely control n because other members of the homologous series have similar stoichiometry and a phase with the desired n is degenerate in energy with syntactic intergrowths among similar n values; this challenge is amplified as n increases. To improve the ability to synthesize a targeted phase with precise control of the atomic layering, we apply the x-ray diffraction (XRD) approach developed for superlattices of III–V semiconductors to measure minute deviations from the ideal structure so that they can be quantitatively eradicated in subsequent films. We demonstrate the precision of this approach by improving the growth of known Ruddlesden–Popper phases and ultimately, by synthesizing an unprecedented n = 20 Ruddlesden–Popper phase, (ATiO3)20AO where the A-site occupancy is Ba0.6Sr0.4. We demonstrate the generality of this method by applying it to Aurivillius phases and the Bi2Sr2Can–1CunO2n+4 series of high-temperature superconducting phases.

We report the epitaxial integration of phase-pure EuO on both single-crystal diamond and on epitaxial diamond films grown on silicon utilizing reactive molecular-beam epitaxy. The epitaxial orientation relationship is (001) EuO ‖ (001) diamond and [110] EuO ‖ [100] diamond. The EuO layer is nominally unstrained and ferromagnetic with a transition temperature of 68 ± 2 K and a saturation magnetization of 5.5 ± 0.1 Bohr magnetons per europium ion on the single-crystal diamond, and a transition temperature of 67 ± 2 K and a saturation magnetization of 2.1 ± 0.1 Bohr magnetons per europium ion on the epitaxial diamond film.

Epitaxial perovskite oxide thin films and heterostructures are a highly active materials research topic generating both fundamental and applied interest. This manuscript reports the roles of oxidation kinetics and film deposition rate on the growth of phase-pure complex oxides by molecular-beam epitaxy, one of the premier techniques for these materials, in a regime that is traditionally described as being governed by thermodynamics. It is found that oxidation kinetics on the film surface are surprisingly important for the growth of PbTiO${}_{3}$ and for formulating a simple kinetic theory to interpret experimental observations. The results are also enlightening to predict the conditions for improved growth of BiFeO${}_{3}$ and other complex oxides by MBE, of high interest to the broad community studying oxide films and heterostructures.

Low temperature magneto-transport properties and electron dephasing mechanisms of phosphorus-doped ZnO thin films grown on (1 1 1) Si substrates with Lu 2 O 3 buffer layers using pulsed laser deposition were investigated in detail by quantum interference and weak localization theories under magnetic fields up to 10 T. The dephasing length follows the temperature dependence with an index p ≈1.6 at higher temperatures indicating electron–electron interaction, yet becomes saturated at lower temperatures. Consistent with photoluminescence measurements and the multi-band simulation of the electron concentration, such behavior was associated with the dislocation densities obtained from x-ray diffraction and mobility fittings, where charged edge dislocations acting as inelastic Coulomb scattering centers were affirmed responsible for electron dephasing. Owing to the temperature independence of the dislocation density, the phosphorus-doped ZnO film maintained a Hall mobility of 4.5 cm 2 V −1 s −1 at 4 K.

Ferroelectric ferromagnets are exceedingly rare, fundamentally interesting multiferroic materials that could give rise to new technologies in which the low power and high speed of field-effect electronics are combined with the permanence and routability of voltage-controlled ferromagnetism. Furthermore, the properties of the few compounds that simultaneously exhibit these phenomena are insignificant in comparison with those of useful ferroelectrics or ferromagnets: their spontaneous polarizations or magnetizations are smaller by a factor of 1,000 or more. The same holds for magnetic- or electric-field-induced multiferroics. Owing to the weak properties of single-phase multiferroics, composite and multilayer approaches involving strain-coupled piezoelectric and magnetostrictive components are the closest to application today. Recently, however, a new route to ferroelectric ferromagnets was proposed by which magnetically ordered insulators that are neither ferroelectric nor ferromagnetic are transformed into ferroelectric ferromagnets using a single control parameter, strain. The system targeted, EuTiO(3), was predicted to exhibit strong ferromagnetism (spontaneous magnetization, approximately 7 Bohr magnetons per Eu) and strong ferroelectricity (spontaneous polarization, approximately 10 microC cm(-2)) simultaneously under large biaxial compressive strain. These values are orders of magnitude higher than those of any known ferroelectric ferromagnet and rival the best materials that are solely ferroelectric or ferromagnetic. Hindered by the absence of an appropriate substrate to provide the desired compression we turned to tensile strain. Here we show both experimentally and theoretically the emergence of a multiferroic state under biaxial tension with the unexpected benefit that even lower strains are required, thereby allowing thicker high-quality crystalline films. This realization of a strong ferromagnetic ferroelectric points the way to high-temperature manifestations of this spin-lattice coupling mechanism. Our work demonstrates that a single experimental parameter, strain, simultaneously controls multiple order parameters and is a viable alternative tuning parameter to composition for creating multiferroics.

Long channel n-type metal oxide semiconductor field effect transistors on thin conventional and strained silicon on insulator substrates have been prepared by integrating gadolinium scandate as high-κ gate dielectric in a gate last process. The GdScO3 films were deposited by electron beam evaporation and subsequently annealed in oxygen atmosphere. Electrical characterization of readily processed devices reveals well behaved output and transfer characteristics with high Ion/Ioff ratios of 106–108, and steep inverse subthreshold slopes down to 66 mV/dec. Carrier mobilities of 155 cm2/Vs for the conventional and 366 cm2/Vs for the strained silicon substrates were determined.

Lanthanum lutetium oxide thin films have been grown on Si substrates by three different techniques: pulsed-laser deposition, molecular beam deposition, and atomic layer deposition. Post-deposition annealing in O2 was performed to improve their electrical properties. Capacitance-voltage and current-voltage measurements reveal well-behaving C-V curves and low leakage current density levels. Most strikingly, a dielectric constant around 30 could be achieved for amorphous thin films of this material. These results are discussed in terms of the microstructural characteristics of the films before and after thermal treatment.

Amorphous LaScO"3 and LaLuO"3thin films have been grown by molecular-beam and pulsed-laser deposition on Si substrates, respectively. The depositions were performed at room temperature, 250 or 450 ^oC. Electrical characterization of the films reveal C-V curves with a small hysteresis and low leakage current densities. LaScO"3 and LaLuO"3 films prepared at room temperature show a dielectric constant of ~17. Much higher @k values of around 30 could be achieved when the films were deposited on heated substrates. We correlate this improvement to the achievement of an oxygen stoichiometry close to the nominal stoichiometric composition.

Ternary rare-earth metal scandate layers deposited using pulsed laser deposition (PLD) were studied as dielectrics for high-k applications. GdScO3, DyScO3 and LaScO3 blanket layers with different nominal thicknesses were deposited directly on 2-inch Si (100) substrates for physical characterizations and 2-inch substrates with a lateral SiO2 isolation structure, for capacitor formation with wet-etched electrodes. High- temperature X-ray diffraction (HT-XRD) and TEM reveal that DyScO3 and GdScO3 remain amorphous up to 1000C. The as- deposited DyScO3 layer on both 1nm chemical SiO2 and HF-last surface of Si shows good interface properties as revealed by C- V curves. The leakage current through the layers is comparable to or even lower than that through HfO2 layers of the same EOT. Material properties show sensitivity to annealing conditions.

Despite their potential application in strain-engineered layer structures, the epitaxial growth of rare earth scandate films on cubic perovskite substrates is not fully understood to date. Here we report on the epitaxy of the orthorhombic GdScO3 and DyScO3 on (001) BaTiO3 and SrTiO3 thin films. In particular, the orientation relationship between the orthorhombic epilayer and the cubic substrate is examined by aberration corrected high-resolution transmission electron microscopy. For all cases investigated, the long axis of the orthorhombic unit cell was found to be perpendicular to the growth direction.

Ferroelectric complex niobates with tetragonal tungsten bronze (TTB) structure are of significant interest for a variety of device applications. For many of these applications thin films are required whose properties, due to the particular structure, are sensitively dependent on the film structure and orientation. Based on the system of the relaxor CaXBa1−XNb2O6 (CBN) and the perovskite substrate SrTiO3 (STO) the crystal orientation relationships between film and substrate are determined as (0 0 1)CBN//{0 0 1}STO, [1 0 0]CBN//〈1 3 0〉STO, and [ 0 1 0 ] CBN / / 〈 1 ¯ 3 0 〉 STO . Employing an advanced imaging technique in an aberration-corrected transmission electron microscope we reveal the atomic configuration of both the cation and oxygen columns at the heterointerface. The interface structure as well as the orientation relations can be understood in terms of lowest-energy considerations based on a near-coincidence site lattice model. These results reveal a pathway for tailoring the film orientation of TTB niobates on perovskites for optimizing the film properties for device applications.

Thin films of ferroelectric calcium barium niobate, CaxBa1−xNb2O6, are deposited on MgO(1 0 0) substrates by pulsed laser deposition. The microstructure of the films is investigated by means of conventional and high-resolution transmission electron microscopy. The observation of plan-view and cross-sectional samples shows that the films are polycrystalline. The grains orient with their c-axis parallel to the normal of the film surface. Two sets of preferential in-plane crystallographic relationships are determined as 〈1 1 0〉CBN//〈4 1 0〉MgO and 〈1 0 0〉CBN//〈3 1 0〉MgO. Chemical reactions occur at the interface between the film and the MgO substrate, leading to the formation of two phases, corundum-type Mg4Nb2O9 and pseudobrookite-type Mg5Nb4O15.

Epitaxial rare-earth scandate thin films of 100–1500 nm in thickness have been prepared by pulsed laser deposition on SrTiO3(100) and MgO(100) substrates. Stoichiometry and crystallinity were investigated by Rutherford backscattering spectrometry/channelling (RBS/C), transmission electron microscopy, and X-ray diffraction. Electrical measurements on microstructured capacitors with a SrRuO3 bottom electrode and Au top contacts reveal dielectric constants of 20 to 27, leakage currents of 0.85 to 6 μA/cm2 at 250 kV/cm, and breakdown fields of 0.6 to 1.2 MV/cm. The optical bandgaps of the films range from 5.5 to 6 eV. The results substantiate the high potential of rare-earth scandates as alternative gate oxides.

Ternary oxides (GdScO 3 , DyScO 3 and LaScO 3 —in general RE ScO 3 whereas RE stands for rare earth) were studied as alternative high- κ -dielectrics. Thin amorphous films were deposited on Si (1 0 0) using pulsed laser deposition (PLD) with two different geometries (on-axis and off-axis). The films were characterized using Rutherford backscattering spectrometry (RBS), XRD, AFM, SEM and capacitors by CV and leakage current measurements. GdScO 3 and DyScO 3 remain in the amorphous phase while heating up to 1000 °C. The films produced in the on-axis-geometry are of higher quality concerning stoichiometry, morphology and electrical properties than the off-axis films. A composition close to the stoichiometry of RE ScO 3 is found. In summary, a film density of 95% of crystalline samples, a surface roughness of about 1 A RMS, a permittivity of about 20 and leakage current densities of 10 −8 A/cm 2 for a film thickness of 5 nm were achieved.

We have characterized thin films of LaScO3 and LaAlO3 which were grown by molecular beam deposition on Si substrates. Samples of LaScO3 were also grown by pulsed laser deposition on MgO substrates. Using transmission studies between 1.5 and 6eV, we have established that low temperature deposition leads to a reduced band gap with respect to the bulk crystal. Furthermore, using spectroscopic ellipsometry from 5to9eV we observe substantial differences in near-band gap absorption between thin and thicker films for both materials. We obtain a band gap of 5.84eV for the thinner film of LaAlO3, whereas we find a band gap of 6.33eV for the thicker film of LaAlO3. Similarly we find band gaps of 5.5 and 5.96eV, respectively, for thin and thick films of LaScO3.

BaTiO 3 bilayer films are deposited on SrTiO 3 substrates under different oxygen pressures by pulsed laser deposition. The structural properties of the bilayers are investigated by means of X-ray diffraction, Rutherford backscattering spectrometry, conventional and high-resolution transmission electron microscopy. The BaTiO 3 layer with the thickness of 115 nm deposited under higher oxygen pressure (3×10 −1 mbar) exhibits a cubic-like structure with lattice parameter a = 0.399 nm . The BaTiO 3 layer with the thickness of 220 nm deposited under lower oxygen pressure (2×10 −3 mbar) shows a c -axis-oriented domain structure with lattice parameters a = 0.401 nm and c = 0.411 nm . The interface of the BaTiO 3 bilayer films is coherent and no interfacial dislocations can be seen over larger regions. The misfit dislocations with Burgers vector of type a 〈1 0 0〉 are observed at the interface between bottom BaTiO 3 layer and SrTiO 3 substrates.

Thin films of rare-earth scandates (RE ScO"3) as well as multi-layers of scandates and titanates have been prepared using pulsed laser deposition. Epitaxial films were grown on SrRuO"3/SrTiO"3(100) as well as amorphous films on silicon substrates. The epitaxial films are investigated to measure the physical properties of the crystalline material. Electrical measurements (CV, leakage current) show for example high @e"r>20 for the scandates and @e"r>35 for the epitaxial and amorphous multi-layer films. A diffusion of the new materials into silicon is not observed.

In order to explore the possibility of bandgap engineering in binary oxide insulators we studied photoconductivity of nanometer-thin Hf oxide layers containing different fractions of cations of another sort (Si, Al, Sr, or Ce) deposited on (100)Si. The smallest bandgaps of the Hf:Al and Hf:Ce oxides are close to the values found in elemental Al"2O"3 (6-6.2eV) and HfO"2 (5.6eV), respectively, and show little sensitivity to the concentration of Al or Ce. This result suggests that the oxide sub-network with the largest bandgap preserves its gap energy, while development of a narrower gap is prevented, likely, by dilution of the second cation sub-network. In Hf:Si oxide samples photoconductivity thresholds of 5.6-5.9eV, corresponding to the bandgap of HfO"2, were observed for all studied Si concentrations, suggesting phaseseparation to occur during deposition. Photoconductivity of SrHfO"3 exhibits two thresholds, at 4.4 and 5.7eV, which are close to the bandgaps of elemental SrO"2 and HfO"2, respectively. These gap values indicate the phase separation also to occur in this binary oxide. Through this work photoconductivity is demonstrated to be a feasible method to trace phase separation in binary oxides, even in nanometer-thin layers.

LaLuO 3 thin films have been deposited with atomic layer deposition on Si substrates using β-diketonate compounds for the rare earth metals and ozone as the oxygen source. Subsequently, the films were investigated regarding their chemical composition, morphology, and electrical characteristics. The as deposited films are amorphous, uniform, and smooth but reveal an excess of oxygen and a low κ -value of ∼ 17. Oxygen annealing of the films at 800 °C for 5 min leads to a reduction of the oxygen content and a dramatic increase of the permittivity to ∼ 30 but also to a crystallization of thick films.

Epitaxial thin films of LaLuO3 were deposited on SrTiO3(100) and SrRuO3/SrTiO3(100) or SrRuO3/LaAlO3(100) substrates using pulsed-laser deposition. They were investigated by means of Rutherford backscattering spectrometry, X-ray diffraction, transmission electron microscopy and atomic force microscopy. Smooth, c-axis oriented films with a channeling minimum yield of 3% were obtained. The electrical characterization of Au/LaLuO3/SrRuO3/SrTiO3(100) and Au/LaLuO3/SrRuO3/LaAlO3(100) metal–insulator–metal capacitor stacks revealed a dielectric constant of κ>45 and a breakdown field of 2 MV/cm for 100 nm thick epitaxial LaLuO3 films.

Insulated gate n-channel enhancement mode InGaAs field effect transistors with the GdScO 3 high-k dielectric have been fabricated and studied. The low frequency noise was high indicating a high interface density of traps. Trap density and its dependence on the gate voltage have been extracted from the noise and conductance measurements.

The effects of film thickness and epitaxial strain on the magnetic properties of commensurate EuO thin films grown on single crystalline (001) yttria-stabilized zirconia (YSZ) and (110) LuAlO3 substrates are presented. Magnetic measurements show a reduction in the Curie temperature (TC) for EuO/YSZ films thinner than ∼10 nm. Additionally, the EuO/LuAlO3 films exhibit a systematically lower TC than the corresponding EuO/YSZ films. This further reduction in TC is attributed to the effect of biaxial tensile strain arising from lattice mismatch: 0.0% for EuO/YSZ and +1.0% for EuO/LuAlO3.

The electron energy band alignment between (100)Si and several complex transition/rare earth (RE) metal oxides (LaScO3, GdScO3, DyScO3, and LaAlO3, all in amorphous form) is determined using a combination of internal photoemission and photoconductivity measurements. The band gap width is nearly the same in all the oxides (5.6-5.7 eV) yielding the conduction and valence band offsets at the Si/oxide interface of 2.0+/-0.1 and 2.5+/-0.1 eV, respectively. However, band-tail states are observed and these are associated with Jahn-Teller relaxation of transition metal and RE cations which splits their d* states. (C) 2004 American Institute of Physics.

The effect of lutetium doping on the structural, electronic, and magnetic properties of epitaxial EuO thin films grown by reactive molecular-beam epitaxy is experimentally investigated. The behavior of Lu-doped EuO is contrasted with doping by lanthanum and gadolinium. All three dopants are found to behave similarly despite differences in electronic configuration and ionic size. Andreev reflection measurements on Lu-doped EuO reveal a spin-polarization of 96% in the conduction band, despite non-magnetic carriers introduced by 5% lutetium doping. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4723570]

Rare earth doping is a standard, yet experimentally poorly understood method to increase the Curie temperature (T-C) of the ferromagnetic semiconductor EuO. Here, we report on the charge carrier density (n) and the T-C of commonly used 4.2 at. % Gd-doped EuO films grown by molecular-beam epitaxy on (110) oriented YAlO3 substrates at various substrate temperatures (T-sub). Increasing T-sub leads to a decrease in n and T-C. For high substrate temperatures the Gd-doping is rendered completely inactive: n and T-C drop to the values of undoped EuO. (C) 2011 American Institute of Physics. [doi:10.1063/1.3563708]

We analyze both experimentally (where possible) and theoretically from first-principles the dielectric tensor components and crystal structure of five classes of Pbnm perovskites. All of these materials are believed to be stable on silicon and are therefore promising candidates for high-K dielectrics. We also analyze the structure of these materials with various simple models, decompose the lattice contribution to the dielectric tensor into force constant matrix eigenmode contributions, explore a peculiar correlation between structural and dielectric anisotropies in these compounds and give phonon frequencies and infrared activities of those modes that are infrared-active. We find that CaZrO3, SrZrO3, LaHoO3, and LaYO3 are among the most promising candidates for high-K dielectrics among the compounds we considered.

Homoepitaxial Sr1+xTiO3+delta films with -0.2

We have developed the means to grow BiMnO3 thin films with unparalleled structural perfection by reactive molecular-beam epitaxy and determined its band gap. Film growth occurs in an adsorption-controlled growth regime. Within this growth window bounded by oxygen pressure and substrate temperature at a fixed bismuth overpressure, single-phase films of the metastable perovskite BiMnO3 may be grown by epitaxial stabilization. X-ray diffraction reveals phase-pure and epitaxial films with omega rocking curve full width at half maximum values as narrow as 11 arc sec (0.003 degrees). Optical absorption measurements reveal that BiMnO3 has a direct band gap of 1.1 +/- 0.1 eV. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3457786]

Rare earth doping is the key strategy to increase the Curie temperature (T C ) of the ferromagnetic semiconductor EuO. The interplay between doping and charge carrier density (n), and the limit of the T C increase, however, are yet to be understood. We report measurements of n and T C of Gd-doped EuO over a wide range of doping levels. The results show a direct correlation between n and T C , with both exhibiting a maximum at high doping. On average, less than 35% of the dopants act as donors, raising the question about the limit to increasing T C .

Mc 2009. Microscopy Conference, Graz, Austria. 30 August - 4 September 2009. First Joint Meeting Of Dreiländertagung And Multinational Congress On Microscopy.

We have studied the effect of biaxial strain on thin films of (001) La0.7Sr0.3MnO3. We deposited films by reactive molecular-beam epitaxy on different single crystalline substrates, varying the substrate-induced biaxial strain from -2.3% to +3.2%. Magnetization and electrical transport measurements reveal that the dependence of the Curie temperature on biaxial strain is in very good agreement with the theoretical predictions of Millis et al. [J. Appl. Phys. 83, 1588 (1998)]. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3213346]

Phase-pure, stoichiometric, unstrained, epitaxial (001)-oriented EuTiO3 thin films have been grown on (001) SrTiO3 substrates by reactive molecular-beam epitaxy. Magnetization measurements show antiferromagnetic behavior with T-N=5.5 K, similar to bulk EuTiO3. Spectroscopic ellipsometry measurements reveal that EuTiO3 films have a direct optical band gap of 0.93 +/- 0.07 eV.

In this Comment we clarify the misconceptions expressed by Panguluri et al. [R. P. Panguluri, T. S. Santos, E. Negusse, J. Dvorak, Y. Idzerda, J. S. Moodera, and B. Nadgorny, Phys. Rev. B 78, 125307 (2008)] regarding the experimental procedures and data interpretation used in our work [A. Schmehl, V. Vaithyanathan, A. Herrnberger, S. Thiel, C. Richter, M. Liberati, T. Heeg, M. Rockerath, L. F. Kourkoutis, S. Muhlbauer, P. Boni, D. A. Muller, Y. Barash, J. Schubert, Y. Idzerda, J. Mannhart, and D. G. Schlom, Nature Mater. 6, 882 (2007)]. We show that our experimental procedures and resulting data are direct consequences of the materials and sample geometries we used and demonstrate that our carefully chosen approach has advantages over the techniques used in the criticizing publication.

Deposition of earth alkali titanate thin films on different substrates allows to tune the strain and, as consequence, their dielectric properties. In this sense, the large range of available lattice constants in rare earth scandates make them very useful candidates to serve as substrate materials for epitaxial growth. In this work we have employed aberration corrected high-resolution transmission electron microscopy (HRTEM) to quantify the strain in different scandate/titanate multilayers by using the geometrical phase analysis method [1]. Besides, we applied electron energy loss spectroscopy (EELS) and ab initio calculations to obtain information about the effect of the strain on the electronic structure of these materials.

Long channel n-MOSFETs on thin SOI and sSOI substrates have been prepared integrating gadolinium scandate as high-kappa gate dielectric in a gate last process. The GdScCh films were deposited by electron beam evaporation and subsequently annealed in oxygen atmosphere. Electrical characterization of readily processed devices reveal well behaved output and transfer characteristics with high Ion/Ioff ratios of 106-108 and steep inverse subthreshold slopes of

Using molecular-beam epitaxy, we demonstrate the adsorption-controlled growth of epitaxial EuO films on single crystalline (110) YAlO3 substrates. Four-circle x-ray diffraction (XRD) reveals phase-pure, epitaxial, (001)-oriented films with rocking curve full width at half maxima as narrow as 34 arc sec (0.0097 degrees). The critical thickness for the onset of relaxation of (001) EuO on (110) YAlO3 (similar to 2% lattice mismatch) was determined from XRD measurements to be 382 +/- 25 angstrom. A saturation magnetization of 6.96 +/- 0.07 mu(B)/Eu, a value close to the theoretical limit of 7 mu(B)/Eu, is observed. (C) 2008 American Institute of Physics.

Doped EuO is an attractive material for the fabrication of proof-of-concept spintronic devices. Yet for decades its use has been hindered by its instability in air and the difficulty of preparing and patterning high-quality thin films. Here, we establish EuO as the pre-eminent material for the direct integration of a carrier-concentration-matched half-metal with the long-spin-lifetime semiconductors silicon and GaN, using methods that transcend these difficulties. Andreev reflection measurements reveal that the spin polarization in doped epitaxial EuO films exceeds 90%, demonstrating that EuO is a half-metal even when highly doped. Furthermore, EuO is epitaxially integrated with silicon and GaN. These results demonstrate the high potential of EuO for spintronic devices.

International audience; We investigate the suitability of an epitaxial CaTiO3 buffer layer deposited onto (100)Si by reactive molecular-beam epitaxy (MBE) for the epitaxial integration of thecolossal magnetoresistive material La0.7Sr0.3MnO3 with silicon. The magnetic andelectrical properties of La0.7Sr0.3MnO3 films deposited by MBE on CaTiO3-bufferedsilicon (CaTiO3/Si) are compared with those deposited on SrTiO3-buffered silicon(SrTiO3/Si). In addition to possessing a higher Curie temperature and a highermetal-to-insulator transition temperature, the electrical resistivity and 1/ f noise levelat 300 K are reduced by a factor of two in the heterostructure with the CaTiO3 bufferlayer. These results are relevant to device applications of La0.7Sr0.3MnO3 thin filmson silicon substrates.

Rare earth scandate thin films (GdScO3 and DyScO3) were investigated with respect to future high-k applications. They were deposited on (100) silicon substrates using either pulsed laser deposition (PLD) or electron beam evaporation. The investigation of the films was done by means of Rutherford backscattering spectrometry, high-temperature X-ray-diffractometry, X-ray reflectometry, spectroscopic ellipsometry, transmission electron microscopy (TEM) and atomic force microscopy. For the electrical characterization capacitor stacks were prepared. Both materials show very promising characteristics independent from the deposition technique used. The films are stoichiometric and amorphous and exhibit a smooth surface (roughness RMS < 1 Å). The amorphous phase is stable up to 1000°C. The electrical characterization revealed featureless C-V-curves with a small hysteresis. From CET plots (CET = capacitance equivalent thickness) k-values between 20 and 23 could be extracted. The electron beam evaporation produces films with a better homogeneity and a thinner interfacial silicon dioxide and therefore a smaller CET value as confirmed by TEM. The leakage current density of the film with CET = 1.5 nm was as low as 7.7x10-4 A/cm2.

Gadolinium scandate thin films deposited on silicon substrates using electron beam evaporation were investigated. Measurements with Rutherford backscattering spectrometry, high temperature x-ray diffraction, x-ray reflectometry, transmission electron microscopy, and atomic force microscopy were performed. A stoichiometric transfer of material from the source to the substrate in high vacuum could be demonstrated. Homogeneous, amorphous, and smooth films (root mean square surface roughness < 1 A) stable up to 1000 degrees C were obtained. Electrical characterization of capacitor stacks revealed a dielectric constant of approximate to 23, C-V curves with small hysteresises and low leakage current densities (770 mu A/cm(2) for a capacitance equivalent thickness of 1.5 nm). (c) 2006 American Institute of Physics.

Ternary oxides, GdScO3, DYScO3, and LaScO3, deposited by pulsed laser deposition using ceramics targets of stoichiometric composition, were studied as alternative high-k gate dielectrics on (100) Si. Their physical characterization was done using Rutherford backscattering, spectroscopic ellipsometry, x-ray diffraction, and transmission electron microscopy on blanket layers deposited on (100) Si, and electrical characterization on capacitors. It is found that DYScO3 and GdScO3 preserve their amorphous phases up to 1000 degrees C. Other encouraging properties for high k applications were demonstrated, including k-value similar to 22, almost no hysteresis or frequency dispersion in C-V curves, and leakage current reduction comparable to that of HfO2 of the same equivalent oxide thickness. (C) 2005 American Institute of Physics.

Single crystalline (0001)ZnO films were grown by pulsed-laser deposition on (111) Si substrates containing thin Sc2O3 buffer layers (1 and 5nm) which were prepared by molecular-beam epitaxy at 700 ◦ C. Both x-ray diffraction and transmission electron microscopy reveal that the ZnO films grown at 240 and 400 ◦ C are highly crystalline with good epitaxy. The commonly seen amorphous SiOx layer has been successfully eliminated from the interface between the ZnO/Sc2O3 film and (111) Si substrate, resulting in improved electrical properties. Rectifying effects are observed in the heterojunction exhibiting a turn-on voltage of 1.08V and an ideality factor of 17.7. The room temperature mobility is 65cm 2 V −1 s −1 . A donor binding energy of 46.7meV is determined by temperature-dependent photoluminescence measurements.

Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010.

Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010.

Extended abstract of a paper presented at MC 2007, 33rd DGE Conference in Saarbrücken, Germany, September 2 – September 7, 2007

Ferroelectric domain orientations have been mapped using piezo-force microscopy, allowing the calculation and statistical analysis of interfacial polarization angles, the head-to-tail or head-to-head configuration, and any cross-coupling terms. Within 1 mu m(2) of an epitaxial (001)(p)-oriented BiFeO3 film, there are >40 mu m of linear domain boundary based on over 500 interfaces. 71 degrees domain walls dominate the interfacial polarization angles, with a 2:1 preference for uncharged head-to-tail versus charged head-to-head boundary types. This mapping technique offers a unique perspective on domain boundary distributions, important for ferroelectric and multiferroic applications where domain wall parameters are critical. (C) 2011 American Institute of Physics. [doi:10.1063/1.3643155]