In this letter we report on cubic CdS thin films with low resistivity by chemical bath deposition (CBD) technique and subsequent annealings in S₂ and H₂+In. Low temperature photoluminescence, x rays, and transmission spectra support the assumption that S₂ annealings contribute to fill the vacancies in the as‐deposited films leading to an enlargement of the CdS cubic cell. This fact is revealed by an increase in interplanar distances, evanescence of the PL red broad band, and decrease in band‐gap energies. Cubic phase remains after H₂+In annealing at higher temperatures. A resistivity as low as 11 Ω cm was obtained at an optimum annealing temperature of 350 °C.

Chemically—driven isothermal close space vapour transport was used to prepare pure MoO ₂ thin films which were eventually converted to MoO ₃ by annealing in air. According to temperature-dependent Raman measurements, the MoO ₂ /MoO ₃ phase transformation was found to occur in the 225 °C–350 °C range while no other phases were detected during the transition. A clear change in composition as well as noticeable modifications of the band gap and the absorption coefficient confirmed the conversion from MoO ₂ to MoO ₃ . An extensive characterization of these two pure phases was carried out. In particular, a procedure was developed to determine the dispersion relation of the refractive index of MoO ₂ from the shift of the interference fringes of the used SiO ₂ /Si substrate. The obtained data of the refractive index was corrected taking into account the porosity of the samples calculated from elastic backscattering spectrometry. The Debye temperature and the residual resistivity were extracted from the electrical resistivity temperature dependence using the Bloch–Grüneisen equation. MoO ₃ converted samples presented a very high resistivity and a typical semiconducting behavior. They also showed intense and broad luminescence spectra composed by several contributions whose temperature behavior was examined. Furthermore, surface photovoltage spectra were taken and their relation with the photoluminescence is discussed.

Photoluminescence (PL) studies in GaN thin films grown by infrared close space vapor transport (CSVT-IR) in vacuum are presented in this work. The growth of GaN thin films was done on a variety of substrates like silicon, sapphire and fused silica. Room temperature PL spectra of all the GaN films show near band-edge emission (NBE) and a broad blue and green luminescence (BL, GL), which can be seen with the naked eye in a bright room. The sample grown by infrared CSVT on the silicon substrate shows several emission peaks from 2.4 to 3.22 eV with a pronounced red shift with respect to the band gap energy. The sample grown on sapphire shows strong and broad ultraviolet emission peaks (UVL) centered at 3.19 eV and it exhibits a red shift of NBE. The PL spectrum of GaN films deposited on fused silica exhibited a unique and strong blue-green emission peak centered at 2.38 eV. The presence of yellow and green luminescence in all samples is related to native defects in the structure such as dislocations in GaN and/or the presence of amorphous phases. We analyze the material quality that can be obtained by CSVT-IR in vacuum, which is a high yield technique with simple equipment set-up, in terms of the PL results obtained in each case.