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Photothermal techniques rely on light induced heating mechanisms to evaluate various optical, thermal and electronic properties of materials. In this work, photothermal beam deflection technique is employed to investigate non-radiative transitions occurring within the conduction band and defect bands of β-InS thin films. Heat generation from β-InS thin films is triggered using laser beams of wavelength 488, 532 and 632 nm. A probe laser beam of wavelength 546 nm is used to measure the heat generation and distribution in the samples. Thermal diffusivity ( D), electronic carrier mobility ( μ), lifetime $$\left( \tau \right)$$ and surface recombination velocity ( V) are measured by fitting the theoretical and experimental photothermal response. The photothermal response and transport properties of the β-InS thin films with varying percentage of chlorine as dopant is studied to understand the role of chlorine. The presence of chlorine in these films have increased the electronic mobilty and carrier lifetime by an order of 10 by passivation of surface defects. [ABSTRACT FROM AUTHOR]

ZnSeTe films were deposited by the electron beam evaporation technique at a substrate temperature of 300 °C on glass and ITO coated GaAs substrates. The films exhibited cubic structure. Photoluminescence (PL) was studied at room temperature using an excitation wavelength of 320 nm. The films deposited on glass substrates exhibited band edge luminescence and self activated luminescence bands at 2.69 and 2.39 eV respectively. Atomic force microscopic studies indicated that the grain size increased with increase of Te content in the ternary. PL studies on the ZnSeTe/GaAs/ITO strucrure was made with an excitation of 265 nm. The films exhibited band edge emission at 2.33 eV which confirms the incorporation of Te in ZnSe. Another peak ar 2.56 eV was also observed. [ABSTRACT FROM AUTHOR]

ZnTeSe films were deposited on glass substrates kept at 200 °C by the electron beam evaporation technique. These films exhibited cubic structure and the lattice parameter increased with increase of Tellurium concentration in the films which confirmed the solid solution formation. The grain size is found to increase with Te content. The dislocation density and lattice strain show a decreasing trend with increasing of Te content. Band gap values of 2.73 eV, 2.63 eV, 2.52 eV and 2.41 eV have been calculated for the films of composition ' x' = 0.2, 0.4, 0.6 and 0.8, respectively, which confirmed the formation of solid solution between ZnSe and ZnTe. Refractive index of the films increased from 2.535 to 2.826 as the concentration of Te increased. All the films showed high resistivity values. Laser Raman spectral studies of ZnTeSe revealed LO phonon frequencies whose values are located in between the LO phonon frequencies of ZnSe and ZnTe. [ABSTRACT FROM AUTHOR]

Silver diffusion enhanced the properties of Indium sulfide (In2S3) films making it highly suitable buffer layer for photovoltaic applications. Thin layer of silver deposited over In2S3 films diffused into In2S3 films in ‘as-deposited’ condition itself creating doping effect. A significant enhancement in crystallinity and grain size could be obtained up to an optimum percentage of doping concentration. This optimum value showed dependence on thickness and atomic ratio of indium and sulfur in the film. Band gap decreased up to the optimum value of doping and thereafter it increased. Electrical studies showed a decrease in resistivity due to doping. Sample having the optimum doping was found to be more photosensitive and low resistive when compared with the pristine sample. These results proved that silver diffused indium sulfide surpasses pristine sample for crystallinity and photosensitivity. Doping β-In2S3 film with optimum amount of silver modified the structural and electrical properties of the films favorably so that the Ag electrodes given to the ITO/CuInS2/In2S3 cell structure itself acted as a doping agent for the In2S3 layer, enhancing the cell efficiency to 9.5% (John et al. Sol Energy Mater Sol Cells 89:27, 2005). [ABSTRACT FROM AUTHOR]