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Abstract: SiO2/CdTe nanocomposites were prepared in thin film form on quartz substrate using a multi-target dc magnetron sputtering system. The films were deposited at high pressure (∼15Pa) with deposition temperature ranging from 240 to 260K. The films were characterized by microstructural studies and phase modulated spectroscopic ellipsometry along with optical transmittance measurements. The ellipsometric spectra were recorded in the wavelength range of 300–1200nm. The spectra were fitted theoretically with an appropriate model assuming a realistic sample structure. Variations of refractive index, extinction coefficient and dielectric constant with wavelength have been derived. [Copyright &y& Elsevier]

SiO2/CdTe/SiO2 composite films in the nanocrystalline form were deposited using a multi-target magnetron sputtering system onto fused silica substrates at a system pressure ∼15 Pa. Different sets of nanocomposite films with different ratios of the sizes of the nanocrystallites (d) and intercrystallite distances (s) were deposited by changing the relative time of sputtering during sequential sputtering of the targets. The films were characterized by measuring optical, electrical and microstructural properties. Variation of electrical conductivity with temperature indicated Efros hopping within the Coulomb gap to be the predominant carrier transport process in these composite films. A crossover from ‘soft’ to ‘hard’ Coulomb gap was observed with lowering of film temperature. Photoluminescence measurements were carried out in the temperature range 80–300 K. The experimental results were compared with those calculated from the empirical relations regarding the temperature dependence of band-edge energy. [Copyright &y& Elsevier]

Abstract: Deep levels in polycrystalline p-Cu2O/i-ZnO/n-ZnO/glass photovoltaic structures were studied by deep level transient spectroscopy (DLTS). Post-deposition crown-ether cyanide (CN) treatments of the samples were performed with the variation of time. DLTS spectra for all samples showed the presence of two traps localized at 0.2eV and 0.5eV from the top of the valence band. Effects of defect passivation and improvement of cell performance were demonstrated with the cyanide treated samples. Optimum time of cyanide treatment was found to be 3min. Cell performance was increased from 0.4% to 0.7% for the samples undergoing the optimum post-deposition cyanide treatment. [Copyright &y& Elsevier]