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Cu2O homojunction solar cells were fabricated using potentiostatic electrodeposition technique. n-Cu2O thin films were grown in an acetate bath while p-Cu2O thin films were grown in a lactate bath. In the growth of n-Cu2O films, cupric acetate concentration, pH and temperature of the bath, deposition potential and duration (film thickness) and annealing temperature were investigated. In the growth of p-Cu2O on n-Cu2O, concentration of copper sulphate and lactic acid solutions, pH and temperature of the bath, deposition potential and duration were investigated. In addition, the procedure of sulfidation of p-Cu2O film surface using (NH4)2S vapor, before depositing Au front contact, was also optimized to enhance the photoactive performance. The structural, morphological and optoelectronic properties of the Cu2O films were investigated using scanning electron microscopy (SEMs), high energy X-ray diffraction (HEXRD), hard X-ray photoelectron spectroscopy (HAXPES), spectral response and current–voltage (J-V) measurements. The best Cu2O homojunction solar cell exhibited Voc = 460 mV, Jsc = 12.99 mA·cm−2, FF = 42% and η = 2.51%, under AM 1.5 illumination. Efficiency enhancement with the record high Jsc value for the Cu2O homojunction solar cell has mainly been due to the optimization of pH of the n-Cu2O deposition bath and lactic acid concentration of the p-Cu2O deposition bath. [ABSTRACT FROM AUTHOR]

A combined microscopic, i.e., powder and single crystal x-ray diffraction and inelastic x-ray scattering, and macroscopic, i.e., heat capacity, characterization was carried out on YB 66 between 10 and 400 K. The system crystallizes in a rather large unit cell with a lattice parameter of about 23.4 Å at room temperature. The volume thermal expansion coefficient is found to be 3.9 × 10 − 5 K − 1 at 295 K. A high Debye temperature above 1000 K was determined using several methods, 1043 (25) K , from heat capacity measurements, 1430 (59) K , from elastic constants measurements, and 1690 (198) K , from thermal expansion measurements. The thermal transport is modeled as a collection of Einstein oscillators with an Einstein temperature of 194 (2) K. The C 11 and C 44 elastic constants are above 400 and 150 GPa , respectively. The average speed of sound in YB 66 is estimated to be 9631 (380) m / s , similar to the average speed of sound in corundum, 10 000 m / s. The large volume of the unit cell and the stiffness of the crystal structure make YB 66 a promising candidate for high-resolution x-ray monochromatization applications. Candidate reflections for high-resolution resonant inelastic x-ray scattering are indicated and potential pitfalls relevant to the quality of crystals and multi-beam cases are mentioned. [ABSTRACT FROM AUTHOR]

BaTi[O.sub.3]/SrTi[O.sub.3](001) epitaxial thin films are prepared at various growth rates by pulsed laser deposition and their heterostructures are evaluated. The results have indicated that the critical thickness of BaTi[O.sub.3]/SrTi[O.sub.3](001) epitaxial thin films can be controlled by the deposition rate and that the critical thickness has increased with increasing deposition rate.

Grazing-incidence x-ray diffraction was used to study Si/Ge films grown by surfactant mediated molecular beam epitaxy on Si(001).

We present an indirect method of estimating the strength of a shock wave, allowing on line monitoring of its reproducibility in each laser shot. This method is based on a shot-to-shot measurement of the X-ray emission from the ablated plasma by a high resolution, spatially resolved focusing spectrometer. An optical pump laser with energy of 1.0 J and pulse duration of ∼660 ps was used to irradiate solid targets or foils with various thicknesses containing Oxygen, Aluminum, Iron, and Tantalum. The high sensitivity and resolving power of the X-ray spectrometer allowed spectra to be obtained on each laser shot and to control fluctuations of the spectral intensity emitted by different plasmas with an accuracy of ∼2%, implying an accuracy in the derived electron plasma temperature of 5%-10% in pump-probe high energy density science experiments. At nano- and sub-nanosecond duration of laser pulse with relatively low laser intensities and ratio Z/A∼0.5, the electron temperature follows Te∼Ilas2/3. Thus, measurements of the electron plasma temperature allow indirect estimation of the laser flux on the target and control its shot-to-shot fluctuation. Knowing the laser flux intensity and its fluctuation gives us the possibility of monitoring shot-to-shot reproducibility of shock wave strength generation with high accuracy. [ABSTRACT FROM AUTHOR]

The ferroelectric properties and crystal structure of doped HfO2 thin films were investigated for different thicknesses, electrode materials, and annealing conditions. Metal-ferroelectric-metal capacitors containing Gd:HfO2 showed no reduction of the polarization within the studied thickness range, in contrast to hafnia films with other dopants. A qualitative model describing the influence of basic process parameters on the crystal structure of HfO2 was proposed. The influence of different structural parameters on the field cycling behavior was examined. This revealed the wake-up effect in doped HfO2 to be dominated by interface induced effects, rather than a field induced phase transition. TaN electrodes were shown to considerably enhance the stabilization of the ferroelectric phase in HfO2 compared to TiN electrodes, yielding a Pr of up to 35 μC/cm2. This effect was attributed to the interface oxidation of the electrodes during annealing, resulting in a different density of oxygen vacancies in the Gd:HfO2 films. Ab initio simulations confirmed the influence of oxygen vacancies on the phase stability of ferroelectric HfO2. [ABSTRACT FROM AUTHOR]

BaTiO3/SrTiO3(001) epitaxial thin films were prepared at various growth rates by pulsed laser deposition, and their heterostructures were evaluated by synchrotron x-ray diffraction measurements and cross-sectional scanning transmission electron microscopy observations. In a film grown at a low deposition rate (0.01 nm/s), misfit dislocations are found near the interface and a fully relaxed BaTiO3 thin film grows epitaxially on the substrate. On the other hand, a film grown at a high deposition rate (0.04 nm/s) consists of strained and relaxed BaTiO3 lattices. Our results showed that the critical thickness of BaTiO3/SrTiO3(001) epitaxial thin films can be controlled by the deposition rate and that the critical thickness increases with increasing deposition rate, and by adjusting the deposition rate, we were able to prepare epitaxial thin films consisting of fully strained BaTiO3, partially strained BaTiO3, or fully relaxed BaTiO3. [ABSTRACT FROM AUTHOR]

The adsorption of water molecules on an oxygen-predosed p(2×2)-Ni(111)–O surface was studied by surface x-ray diffraction and infrared reflection absorption spectroscopy (IRAS) at temperature of 25 and 140 K. Precise structures including adsorbed water, predosed oxygen, and substrate nickel atoms at these two temperatures were determined by x-ray structural analysis. It was found that water molecules adsorb on oxygen additive sites, forming a hydrogen bond at 25 K. A predosed 2×2 oxygen atom appears to accommodate one, two, or three water molecules at positions relating to threefold rotation symmetry. When the surface temperature was raised to 140 K, water molecules appear at an atop site of Ni. The distance between Ni and the oxygen atoms of a monomer water molecule was found to be 0.2241(22) nm. The adsorbed water molecule induces buckling and a lateral shift of the substrate nickel. The IRAS results provided evidence regarding the existence of two distinct adsorption sites. Water molecules in the low-temperature phase exhibit bands from both hydrogen-bonded νOD and free OD stretchings, while those in the high-temperature phase lie flat with a molecular plane parallel to the surface. [ABSTRACT FROM AUTHOR]

An as-grown MgB2 crystalline thin film is fabricated at a low temperature of 270 degree C on an in-plane-lattice near-matched TiZr buffer layer grown on a sapphire Al2O3 (0001) surface. The findings show that the critical temperature and the superconductivity critical current density of MgB2/TiZr/Al2O3 are found to be high compared with those of MgB2/Al2O3.

The ability to systematically vary the flatband potential and the band edge positions of Cu2O by varying the deposition bath pH is considered important in the context of using Cu2O for photocatalytic water splitting. Capacitance-voltage (C-V) and dark and light current-voltage measurements were taken in order to investigate the electronic properties of electrodeposited Cu2O thin films grown in an acetate bath containing a 0.01 M Cupric Acetate having different bath pH values. The Mott-Schottky plots resulting from C-V measurements revealed that the flatband potential and doping density of the films strongly depended on the deposition bath pH. For pH values lower than 7.2, conductivity of Cu2O films remained n-type while it changed to p-type for higher pH values indicating that change of n-type to p-type character of the Cu2O films can be controlled by the bath pH. With increasing pH value, the grain size decreased, while crystal shapes transformed from truncated octahedral to cubic within the tested pH range. A well ordered cubic structure was observed in films deposited at pH 7.8. The rate of deposition decreased at higher pH values leading to thinner films indicating the effect of pH on the film thickness. Calculated band edge positions of conduction and valance bands of the Cu2O films were -4.19 eV and -6.29 eV respectively with respect to the vacuum level. [ABSTRACT FROM AUTHOR]

An as-grown MgB2 crystalline thin film was fabricated at a low temperature of 270°C on an in-plane-lattice near-matched TiZr buffer layer grown on a sapphire Al2O3 (0001) surface. The critical temperature and the superconductivity critical current density of MgB2/TiZr/Al2O3 were found to be high compared with those of MgB2/Al2O3. The film was characterized by using synchrotron x-ray diffraction. The epitaxial relationship in the plane was MgB2[0110]//TiZr[0110]// sapphire [1120]. In-plane-lattice spacings, d//MgB2, d//TiZr, and d//sapphire obtained were 0.268, 0.258, and 0.239 nm for the MgB2(0110), TiZr(0110), and sapphire (1120) planes, respectively. [ABSTRACT FROM AUTHOR]