Optical and Electrical Properties of CdS_1−x Te_x Films

Abstract

Polycrystalline CdS_1−xTe_x films were prepared by coating (l−x) CdS +xCdTe pastes on a borosilicate glass substrate and sintering in nitrogen. The films were sintered in the temperature range 625–700°C to find the phase boundaries of the binary system in this temperature range. The energy band gap and electrical properties of these solid solution semiconductors have been investigated by measuring optical transmission spectra and Hall voltages. At 625°C, the solubility of Te in CdS is x = to 0·10 and the band gap of the S rich solid solution decreases from 2·43 eV for CdS (x=0) to 1·87 eV for CdS_0·9Te_0·l The solubility of S in CdTe is 0·14 and the band gap increases slightly from 1·42 eV for CdS_0·14 Te_0·86 to 1·46 eV for CdTe. The boundaries for the miscibility gap of the binary system at 700°C are x = 0·12 and x = 0·84. Both the carrier concentration and Hall mobility of the alloy semiconductors decreases with increasing Te content. The majority carriers were electrons in the S rich semiconductors and were holes in the Te rich semiconductors. PM/0576