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Abstract: Highly transparent, p-type conducting SnO2:Al films derived from thermal diffusion of a sandwich structure Al/SnO2/Al multilayer thin films deposited on quartz substrate have been prepared by direct current and radio-frequency magnetron sputtering using Al and SnO2 targets. The deposited films were annealed at various temperatures for different durations. The effect of thermal diffusing temperature and time on the structural, electrical and optical performances of SnO2:Al films has been studied. X-ray diffraction results show that all p-type conducting films possessed polycrystalline SnO2 with tetragonal rutile structure. Hall-effect results indicate that 450°C for 4h were the optimum annealing parameters for p-type SnO2:Al films, resulting in a relatively high hole concentration of 7.2×1018 cm−3 and a low resistivity of 0.81Ωcm. The transmission of the p-type SnO2:Al films was above 80%. [ABSTRACT FROM AUTHOR]

Glasses compositions which can be expressed by (100-x)GeS2–xGa2S3 (x=0, 10, 20, 30 mol%), 70GeS2–(30-x)Ga2S3–xCdS (x=0, 10, 15, 20 mol%), and (100-x)GeS2–x[0.5Ga2S3–0.5CdS] (x=0, 10, 20, 30, 40 mol%), were obtained by the melt-quenching technique. Differential scanning calorimetry (DSC) and visible-IR transmission were used to characterize the thermal and optical properties of these glasses, together with refractive index and density measurements. These homogeneous glasses have relatively high glass transition temperatures (338–436 °C), good thermal stabilities, broad transparencies (0.45–11.5 μm), large refractive indices (2.01–2.25), and large densities (2.68–3.18 g cm-3). The long-wavelength cutoff edge is found near 12 μm due to the multiphonon Ge–S and Ga–S vibrations. The compositional dependences of selected properties were also discussed by making reference to the structural variation. [Copyright &y& Elsevier]

Abstract: Amorphous GeSe x (x =2, 4, 6) films were prepared by pulsed laser deposition technique. The optical band gaps and refractive indices of the films were derived from the absorption spectra and optical transmission spectra, respectively. The short-wave absorption edges of the films were well consistent with the ‘non-direct transition’ model proposed by Tauc. The dispersion of the refractive index was analyzed in terms of the single-oscillator Wemple–Di Domenico model. The structural units of the films were characterized using Raman spectroscopy. In addition to the basic structural units of edge-sharing GeSe4/2 tetrahedra, there are Se Se homopolar bonds in Se-rich GeSe4 and GeSe6 films. And Ge Ge bonds exist in stoichiometric GeSe2 film. The results also show that the refractive index of the films changes with the Se content. decreases with the reduction of Se content in the GeSe x films. The changes of were discussed in relation to the structures of the films confirmed by the Raman spectra analysis. [Copyright &y& Elsevier]

Abstract: Amorphous GeSx (x=2, 4, 6) films were prepared by the pulsed laser deposition (PLD) technique. The optical band gaps (E g opt ) and refractive indices of the films were obtained from the optical absorption spectra and transmission spectra, respectively. The short-wave absorption edges of the films were described using the ‘non-direct transition’ model proposed by Tauc. The dispersion of the refractive index was analyzed in terms of the single-oscillator Wemple–Di Domenico model. The structural units of the films were characterized using Raman spectroscopy. In addition to the basic structural units of edge-sharing and corner-sharing [GeS4] tetrahedra, there are S–S homopolar bonds in S-rich GeS4 and GeS6 films while Ge–Ge bonds exist in stoichiometric GeS2 film. The results show that the index of refraction decreases while E g opt increases with the sulphur content in the GeSx films. The changes of E g opt were discussed in relation to the structure of GeSx films, which were confirmed by the Raman spectra analysis. [Copyright &y& Elsevier]

Abstract: Amorphous GeSe2 film was prepared by the pulsed laser deposition technique and annealed at different temperature from 473 to 623K. Using the ‘non-direct transition’ model proposed by Tauc, the short wavelength absorption edges of the films were well fitted and the optical band gaps () were determined. The Tauc slope of the as-deposited film is smaller than those of annealed films, which were proposed as an indicator of the degree of structural randomness of amorphous semiconductors. The refractive index and thickness of the films were calculated from the optical transmission spectra using the Swanepoel method. The index of refraction decreased while increased gradually with increasing the annealing temperature. The thermal-bleaching and thermal-contraction effects were observed, which were interpreted as the reduction in the density of homopolar bonds according to the Raman spectra analysis and the diminution of porous structure in the fragments of the annealed films, respectively. [Copyright &y& Elsevier]

Abstract: Amorphous thin films of GeSe2 and GeSe4 were prepared by the pulsed laser deposition (PLD) technique. Refractive index, thickness and optical band gap () of the films were abtained from the optical transmission spectra and absorption spectra, respectively. Based on the ‘non-direct transition’ model proposed by Tauc, the absorption edges can be well fitted. As an indicator of the degree of structural randomness of amorphous semiconductors, the Tauc slopes of the prepared thin films were discussed. The dispersion of refractive index was analyzed in terms of the single-oscillator Wemple-Di Domenico model. For as-deposited films, after annealing below the glass transition temperature (T g), the drop of refractive index and the increase of can be clearly observed. The thermal-bleaching effect was proposed to the reduction in the density of homopolar bonds confirmed by the Raman spectra analysis. The thermal-contraction effect was ascribed to the elinimination of porous structure of the as-deposited films. [Copyright &y& Elsevier]

Abstract: Amorphous thin films (1− x)(4GeSe2–Ga2Se3)–xKBr (x =0, 0.1, 0.2, 0.3) were prepared by the pulsed laser deposition (PLD) technique. The optical parameters were calculated using the Swanepoel method from the optical transmission spectra. The optical band gap () of the studied films increased while the index of refraction decreased when increased the content of KBr. The Tauc slopes were discussed as an indicator of the degree of structural randomness of amorphous semiconductors. The index of refraction decreased and increased after annealing of as-deposited films below the glass transition temperature. The thermal-bleaching and thermal- contraction effects were observed, which are discussed in relation to the reduction in the density of homopolar bonds confirmed by the Raman spectra analysis and the decreased amount of fragments of the as-deposited films, respectively. [Copyright &y& Elsevier]