Characterization of n-AgIn 5Se 8 polycrystalline semiconductor electrodes by photoelectrochemical techniques

Abstract

Photoelectrochemical techniques were employed to characterise the properties of polycrystalline n-AgIn 5Se 8 samples in aqueous solutions. Flatband potential, donor density, depletion layer width, majority carrier mobility, minority carrier diffusion length and absorption coefficient were determined and discussed in connection with the semiconductor performance. The material stability was examined under reverse bias both in the dark and under illumination. The electrode behaviour was determined for both iodide-polyiodide and neutral sodium sulphate electrolytes. The iodide-polyiodide electrolyte was found to be the most suitable for the formation of liquid junction, but did not stabilise the material during extended illumination and resulted in the growth of a selenium overlayer. The dark corrosion process in the sulphate solution is discussed with reference to the AgIn 5Se 8 electron energy band diagram and to the decomposition potential of possible bond-cleavage reactions.