Structural studies of cadmium telluride thin films

Abstract

The structure of CdTe and its dependence upon evaporation conditions was determined for both 'flash' and boat evaporation at various substrate and boat temperatures. The structure of the thin films was determined by both electron and X-ray diffraction and it was found to be cubic 0 (a = 6.48 A 0 ) with some wurtzxte structure (a = 4.56 A , c = 7.48 A0 ) along with some pure cadmium and tellurium present in the films. In addition the electrical properties and its 9pendence upon these factors was determined. A maximum resistivity of 10 Ohm-metre was measured for films produced by flash evaporation at a substrate temperature of 420 K. The structure and electrical properties of thin films produced by flash deposition were investigated for thin films formed from powder mixes of various ratios. It was found that films formed from powder mixes in the ratio of 2:1, dadinium to tellurium, had a resistivity of 1o4 Ohm-metre, a cubic structure, and no apparent pure cadmium or
Lellurium present when produced using this method. P - N junctions and working solar cells were produced and the dependence of the efficiency of the cells on the top n type layer thickness and incident doping ratio found. Electrical measurements were made on the solar cells but the efficiency was found to be very low (approximately 5 x 10 per cent).