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Indium oxide thin films have been prepared by thermal oxidation of vacuum-deposited indium thin films in air in an open furnace at about 600 K. These indium oxide thin films prepared by thermal oxidation have been examined for optical transparency by measuring their optical absorbance as a function of wavelength. From the optical absorption data, optical band gap and the nature of the forbidden energy gap in the indium oxide thin films have been determined. Electrical conductivity measurements have also been carried out on the above oxide films as a function of temperature during heating and cooling cycles in vacuum. It is found that after the first heating, electrical conductivity increases to a significant extent due to removal of point defect clusters due to annealing which contribute to both carrier generation and scattering. From the thermoelectric power measurements carried out, it has been concluded that electrons are the majority carriers in these indium oxide thin films.

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The fabrication of amorphous silicon/crystalline silicon ͑a-Si:H/c-Si͒ heterojunction solar cell and an understanding of the fundamental conduction mechanism in the device are presented. In the first part, the effect of intrinsic amorphous silicon ͓a-Si:H͑i͔͒ layer thickness on the performance of a-Si:H/c-Si solar cells has been studied. The thickness of a-Si:H͑i͒ layer formed on n-type c-Si substrate was controlled accurately with spectroscopy ellipsometry ͑SE͒. Based on SE results, we discuss the influence of the a-Si:H͑i͒ thickness on the interface quality and thereby cell performance. Then, in the latter part, we present the temperaturedependent current density-voltage curves, in the dark, in order to elucidate the dominant transport mechanisms in a-Si:H/c-Si heterojunction solar cells with and without incorporation of a-Si:H͑i͒ layers. Finally, using optimum design considerations, we obtained a solar cell efficiency of 17.43%.