0000000000121700
AUTHOR
J. M. Recio
Raman measurements on GaN thin films for PV - purposes
Raman scattering (RS) is a very important experimental tool to characterize the optical modes and another elementary excitations of materials. Among other issues it can determine for example the degree of crystalline quality and point defects like local modes. Therefore GaN - thin films and related compounds for photovoltaic purposes and as processed by several systems have been measured by this technique. The films were grown by Molecular Beam Epitaxy (MBE), Close Spaced Vapor Transport (CSVT) and Laser Ablation (LA) with the use of optimal growth parameters and substrates. Gallium nitride crystallizes in the wurtzite structure with 4 atoms in the unit cell and presents 7 allowed Raman mod…
Gallium nitride thin films as processed by several techniques: Their possible applications for PV-devices
We present in this work the characterization studies carried on GaN — thin films as processed by the Close Spaced Vapor Technique (CSVT), Laser Ablation (LA), and Molecular Beam Epitaxy (MBE), under particular growth parameters for each of the three techniques. The films characterization was performed by x-ray diffraction (X-RD), Photoluminescence (PL), Raman spectroscopy, optical transmission, energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). With these results an analysis of the samples was done, with an aim for a possible application of these thin films for PV-devices.
Compression of Silver Sulfide: X-ray Diffraction Measurements and Total-Energy Calculations
[EN] Angle-dispersive X-ray diffraction measurements have been performed in acanthite, Ag2S, up to 18 GPa in order to investigate its high-pressure structural behavior. They have been complemented by ab initio electronic structure calculations. From our experimental data, we have determined that two different high-pressure phase transitions take place at 5 and 10.5 GPa. The first pressure-induced transition is from the initial anti-PbCl2-like monoclinic structure (space group P2(1)/n) to an orthorhombic Ag2Se-type structure (space group P2(1)2(1)2(1)). The compressibility of the lattice parameters and the equation of state of both phases have been determined. A second phase transition to a …