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The effect of nanosecond pulsed excimer laser irradiation on the particle distribution and density of laser-deposited YBa2Cu3O7 thin films was investigated. High-TC YBa2Cu3O7 superconducting thin films with thicknesses varying from 800 to 2000 Å were deposited on (100) LaAlO3 and (100) yttria stabilized zirconia substrates. The as-deposited films were characterized by a distribution of particles on the film’s surface. The effect of controlled low energy density pulses (fluence, E=50–250 mJ/cm2, wavelength λ=248–308 nm, and pulse duration τ=20–45×10-9 s) on these films was investigated. A significant reduction of particles was observed in films after single pulse irradiation at fluences below 150 mJ/cm2. Multiple pulses did not have any further change on the surface morphology. The possible mechanisms for particle removal are also discussed. [ABSTRACT FROM AUTHOR]

The phase structure and magnetic behavior of sputter deposited and annealed Ni–Mn–Ga thin films of varying thickness have been studied. The as-deposited films exhibited quasi-amorphous structure having paramagnetic nature at room temperature. After annealing at 873 K for 30 min ferromagnetic ordering is recovered and the quasi-amorphous structure has changed to nanocrystalline structure. At low film thickness (<300 nm), the annealed films exhibited a mixture of cubic austenite (L2 1 ) and martensite phases while at thickness greater than 1000 nm ordered L1 2 phase was observed. The magnetic properties were found to strongly depend on the structure of the constituent phases in the films. [ABSTRACT FROM AUTHOR]

Abstract: Free-standing polymer electrolyte membranes based on poly(vinyl) pyrrolidone (PVP)/salt(LiBF4) having different amounts of ionic liquid (IL) [EMIM][BF4] were prepared and characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR) spectroscopy, and alternating current (AC) impedance spectroscopic techniques. The DSC results show a shift in T m of PVP with salt/or IL content. TGA and DTGA (first derivative of TGA) results give evidence of the presence of uncomplexed PVP, PVP/salt, and PVP/IL complexes. Signatures of these entities are also present in the dielectric spectra. Complexation of PVP with salt and IL has been confirmed by FT-IR analysis. Electrical conductivity as a function of temperature has been studied for PVP/LiBF4/IL [EMIM][BF4]. Role of IL in changing phase transition, conductivity, and dielectric relaxation frequency has been discussed. [Copyright &y& Elsevier]

Abstract: Polymer electrolyte films of PVP+ x wt% ionic liquid (IL) (1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4]) for x =0, 5, 10, 15, 20, 25wt% have been prepared using solution cast technique. These films were characterized by TGA, DSC, FT-IR and ac impedance spectroscopy techniques. From XRD studies it is found that the inclusion of IL increases the amorphocity of polymeric membranes. DSC thermograms show that the glass transition (T g) and melting temperatures (T m) of PVP shift upon complexation with IL. FT-IR analysis shows the complexation of PVP with IL. Thermogravimetric studies show that PVP decomposes in a single step while PVP/IL membranes exhibit two step decomposition; lower value of decomposition temperature corresponds to the decomposition of PVP/IL complex while the higher decomposition temperature has been attributed to the decomposition of PVP. The decomposition temperature of PVP/IL complex decreases with the increasing amount of IL in the PVP membrane. Temperature dependence of conductivity and dielectric relaxation frequencies have also been studied for PVP and PVP/IL membranes. Both show thermally activated Arrhenius behaviour. [Copyright &y& Elsevier]

Poly(vinyl alcohol) (PVA) and polymer electrolyte (PVA + 15 wt% LiClO4) doped with 20 wt% ionic liquid (IL) (1-ethyl-3-methyl imidazolium ethylsulphate), [EMIM][EtSO4] have been prepared using solution cast technique. These electrolyte films have been characterized using XRD, DSC, TGA, FT-IR and impedance spectroscopic techniques. It has been found that polymer electrolyte film (PVA + 15 wt% LiClO4) + 20 wt% IL shows maximum amorphosity and conductivity. [ABSTRACT FROM AUTHOR]

Abstract: Hf–O–N and HfO2 thin films were evaluated as barrier layers for Hf–Ti–O metal oxide semiconductor capacitor structures. The films were processed by sequential pulsed laser deposition at 300°C and ultra-violet ozone oxidation process at 500°C. The as-deposited Hf–Ti–O films were polycrystalline in nature after oxidation at 500°C and a fully crystallized (o)-HfTiO4 phase was formed upon high temperature annealing at 900°C. The Hf–Ti–O films deposited on Hf–O–N barrier layer exhibited a higher dielectric constant than the films deposited on the HfO2 barrier layer. Leakage current densities lower than 5×10A/cm2 were achieved with both barrier layers at a sub 20Å equivalent oxide thickness. [Copyright &y& Elsevier]

Thin film phosphors have potential applications in field emission flat-panel displays. However, they are limited by the lower cathodoluminescent brightness in comparison to phosphor powders. In this paper, we have investigated the critical parameters that need to be optimized to increase the brightness of phosphor thin films. Specifically, we studied the role of surface roughness and optical properties of the substrate on the brightness of the phosphor films. Thin Y2O3:Eu phosphor films were deposited on various substrates (lanthanum aluminate, quartz, sapphire, and silicon) with thicknesses varying from 50 to 500 nm. A model that accounts for diffuse and specular or scattering effects has been developed to understand the effects of the microstructure on the emission characteristics of the cathodoluminescent films. The results from the model show that both the optical properties of the substrate and the surface roughness of the films play a critical role in controlling the brightness of laser deposited phosphor films. [Copyright &y& Elsevier]

We report ferromagnetism at over 900 K in Cr–GaN and Cr–AlN thin films. The magnetic properties vary as a function of Cr concentration with 60%, and 20%, of the Cr being magnetically active at 3% doping in GaN, and 7% in AlN, respectively. In the GaN sample with the highest magnetically active Cr (60%), channeling Rutherford backscattering indicates that over 70% of Cr impurities are located on substitutional sites. These results give indisputable evidence that substitutional Cr defects are involved in the magnetic behavior. While Cr–AlN is highly resistive, Cr–GaN exhibits properties characteristic of hopping conduction including T-1/2 resistivity dependence and small Hall mobility (0.06 cm2/V s). A large negative magnetoresistance is attributed to the influence of the magnetic field on the quantum interference between the many paths linking two hopping sites. The results strongly suggest that ferromagnetism in Cr–GaN and Cr–AlN can be attributed to the double exchange mechanism as a result of hopping between near-midgap substitutional Cr impurity bands. [ABSTRACT FROM AUTHOR]

Abstract. The microstructure and properties of barium strontium titanate (BST) thin films grown by an in situ ultraviolet-assisted (UV-assisted) pulsed laser deposition (UVPLD) technique are reported in this paper. In comparison with BST films grown by conventional pulsed laser deposition (PLD) under similar conditions, but without UV illumination, the UVPLD-grown films exhibited improved structural, electrical, and optical properties. X-ray photoelectron spectroscopy showed that when exposed to atmosphere, Ba atoms from the outermost layers formed a thin layer of barium carbonate, which negatively affects the film electrical characteristics. UVPLD-grown films exhibited a smaller amount of Ba atoms within the carbonate layer, resulting in better electrical characteristics. The dielectric constant of 40-nm-thick films deposited at 650 Celsius by UVPLD and PLD were determined to be 281 and 172, respectively. The leakage current density of the UVPLD-grown films was in the mid-10[sup -8] A/cm[sup 2] range, a factor of 2 lower than that obtained from PLD-grown films. [ABSTRACT FROM AUTHOR]

Presents a method of laser deposition of diamondlike carbon films at high intensities. Utilization of high titanium: sapphire solid state laser system in the process; Analysis of the film quality using scanning and transmission electron microscopy; Production of smooth, partially transparent films.

Examines low-pressure, low-temperature and remote-plasma deposition of diamond thin films from water-methanol mixtures. Use of cyclotron resonance chemical vapor deposition technique; Temperature ranges and gas pressures of fabricated diamond films; Variation of volume ration of water to methanol to optimize diamond film growth.

Examines the pulsed laser deposition of lithium niobate films grown on sapphire substrates. Effect of oxygen partial pressure on intermediary phase formation; Account on the substrate temperature used in the study; Fabrication of films at oxygen pressure of one Torr.

Presents a corrected reprint of an article on thin films published in a 2003 issue of "Applied Physics Letters".

Abstract. ZnO thin films have been grown on thin Si[sub 3]N[sub 4] membranes and (001) sapphire substrates by an ultraviolet-assisted pulsed laser deposition (UVPLD) technique. The microstructure of the films grown on Si[sub3]N[sub 4] membranes, investigated by transmission electron microscopy, showed that crystalline and textured films can be grown by UVPLD at a substrate temperature of only 100 Celsius. For deposition temperatures higher than 400 Celsius, ZnO films grown on sapphire substrates were found to be epitaxial by Rutherford backscattering (RBS) and X-ray diffraction measurements. The minimum yield of channeling RBS spectra recorded from films deposited at 550 Celsius was around 2% and the FWHM of the rocking curve for the (002) diffraction peak was 0.17 Degrees; these values are similar to those recorded from ZnO layers grown by conventional PLD at 750 Celsius. [ABSTRACT FROM AUTHOR]

Abstract. Thin Y[sub 2]O[sub 3] films have been grown on (100) Si using an in-situ ultraviolet-assisted pulsed laser deposition (UVPLD) technique. When compared to conventional pulsed laser deposited (PLD) films under similar conditions, the UVPLD-grown films exhibited better structural and optical properties, especially those grown at lower substrate temperatures, from 200 Celsius to 400 Celsius. X-ray diffraction investigations showed that the films grown were highly crystalline and textured. According to X-ray photoelectron spectroscopy and Rutherford backscattering spectrometry investigations, UVPLD-grown Y[sub 2] O[sub 3] films have a better overall stoichiometry and contain less physisorbed oxygen than the conventional PLD-grown films. The refractive index values, measured in the range 300-750 nm by using variable-angle spectroscopic ellipsometry, were similar to those of a reference Y[sub 2]O[sub 3] film. [ABSTRACT FROM AUTHOR]

Abstract: We have synthesized and characterized epitaxial and stoichiometric Ba(Zn1/3Ta2/3)O3 (100) dielectric thin films grown on MgO (100) substrates by pulsed laser deposition. Advanced electronic structure calculations were used to guide the interpretation of the experimental data. Zn-enriched targets and high oxygen pressures were used to compensate for Zn loss during film growth. The Ba(Zn1/3Ta2/3)O3 films had an indirect optical band gap of ∼3.0eV and a refractive index of 1.91 in the visible spectral range. Zn–Ta B-site ordering was not observed in the Ba(Zn1/3Ta2/3)O3 thin film X-ray diffraction data. A dielectric constant of 25 and dissipation factor of 0.0025 at 100kHz were measured using the interdigital capacitor method. The Ba(Zn1/3Ta2/3)O3 films exhibited a small thermally activated ohmic leakage current at high fields (<250kVcm–1) and high temperatures (<200°C) with an activation energy of 0.85eV. [Copyright &y& Elsevier]

Abstract: To understand the thermochemistry and determine the rate limiting steps of ZnGeAs2 thin-film synthesis, experiments were performed to measure the (a) thermal decomposition rate and (b) elemental composition and deposition rate of films produced with pulsed laser deposition (PLD). The decomposition rate is kinetically limited with an activation energy of 1.08±0.05eV and an evaporation coefficient of ∼10−3. We show that ZnGeAs2 thin film synthesis is a metastable process with the kinetically-limited decomposition rate playing a dominant role at the elevated temperatures needed to attain epitaxy. Our conclusions are in contrast to those of earlier reports that assumed the growth rate is limited by desorption and the resulting low reactant sticking coefficient. The thermochemical analysis presented here can be used to predict optimal conditions for ZnGeAs2 film physical vapor deposition and thermal processing. [Copyright &y& Elsevier]

Abstract: The synergistic effects of NH3 ambient and ultraviolet illumination on the dielectric properties of hafnia based gate dielectrics are reported in this paper. The films were processed at relatively low temperatures (∼400°C) by pulsed laser ablation and UV oxidation technique. UV illumination and the NH3 ambient created a thin and a denser interfacial layer (at the film–Si interface) comprised of Hfph name="sbnd" />O. As a result of the interfacial layer modification, a leakage current density lower than 10−4 A/cm2 and a dielectric constant of ∼21.7 were extracted from the best samples processed in NH3 and under UV illumination. The nitrogen doped HfO2 also exhibited a thinner interfacial layer (∼12Å) in comparison to the films processed without NH3 ambient. [Copyright &y& Elsevier]

Abstract: ZrC thin films were grown on (001)Si, (111)Si and (0001)sapphire substrates by the pulsed laser deposition (PLD) technique. X-ray diffraction, X-ray reflectivity and Auger electron spectroscopy investigations were used to characterize the structure and composition of the deposited films. It has been found that films grown at temperatures higher than 700°C under very low water vapor pressures were highly textured. Films deposited on (001)Si grew with the (001) axis perpendicular to the substrate, while those deposited on (111)Si and (0001)sapphire grew with the (111) axis perpendicular to the substrate. Pole figures investigations showed that films were epitaxial, with in-plane axis aligned to those of the substrate. [Copyright &y& Elsevier]

ZrO2 and Y2O3 thin films were deposited on Si substrates using pulsed laser deposition in vacuum or oxygen ambient. Angle resolved X-ray photoelectron spectroscopy investigations showed that there was always some oxidation of the Si substrate resulting in the formation of an interfacial layer that could have a deleterious effect on the overall capacitance of the resulting MOS devices. The positions and shape of the metal, the oxygen and the Si XPS peaks suggest that at the temperatures used for deposition (<650 °C) the SiO2 layer is physically mixed with the deposited oxide layer without forming silicate compounds. X-ray reflectivity investigations confirmed the presence of the interfacial layer whose density was found to be higher than that of pure SiO2 but lower than that of the corresponding silicate, corroborating the XPS results. To slow down the substrate oxidation, a low temperature UV-assisted nitridation treatment was performed prior to the deposition of the oxide layer. This UV-assisted treatment resulted in thinner and denser surface passivation layers than those obtained without any treatments indicating an incorporation of nitrogen into the SiO2 network. High-k dielectric layers deposited on such samples exhibited thinner interfacial layers. [Copyright &y& Elsevier]

Ba0.5Sr0.5TiO3, indium tin oxide (ITO), ZnO, and ZrO2 thin films were grown directly on Si substrates by the pulsed laser deposition technique. X-ray photoelectron spectroscopy investigations showed that these films contain oxygen species that are loosely bound, corresponding to what can be described as physisorbed oxygen. This oxygen is responsible for the formation of an interfacial layer at the interface between the Si substrate and the deposited oxide layer during the deposition process. The chemical composition of this interfacial layer consists of SiOx partially mixed with the grown oxide. The trapped oxygen can ensure further growth of the interfacial layer during any post-deposition anneals even when performed in vacuum or inert atmospheres. [Copyright &y& Elsevier]

Thin high-k dielectric Y2O3 and ZrO2 films were grown directly on Si by the pulsed laser deposition (PLD) technique. The interfacial layer formed between the Si and the deposited oxide film was characterized. Since this layer has a detrimental effect on the MOS capacitance of the films, an attempt to modify its characteristics was performed through UV-assisted low-temperature nitridation of the surface to create a barrier layer that suppresses Si diffusion through the interface. It was confirmed by structural characterization that this surface pretreatment results in a thinner interfacial layer. [Copyright &y& Elsevier]

Very thin HfO2 films were deposited directly on Si substrates by the pulsed laser deposition technique in a wide range of substrate temperatures and oxygen pressures to investigate the kinetics of the interfacial layer formation. Angle-resolved X-ray photoelectron spectroscopy (XPS) investigations showed that the interfacial layer formed between the Si substrate and the deposited oxide contains a mixture of HfO2 and SiO2 without any strong evidence to support the formation of a silicate-type compound. X-Ray reflectivity measurements showed that the mass density of the interfacial layer is higher than that of pure SiO2, while spectroscopic ellipsometry measurements showed that the refractive index is higher than that of pure SiO2, therefore corroborating the XPS results. [Copyright &y& Elsevier]