PHOTOCONDUCTIVITY OF CDTE-FILMS

CdTe films were deposited at different substrate temperatures (423-573 K) using the hot wall evaporation technique. The films were polycryst alline in nature with varying grain size (0.06-0.18 mu m) Dark and pho to-conductivities in the films were measured in the temperature range 90-300 K. The conductivity data at low temperatures (< 155 K) were ana lysed by using the quantum mechanical tunnelling of carrier through th e grain boundary barrier model. The relatively large conductivity at t he higher temperature region (> 155 K) was explained by the possible t hermionic emission of the carrier over the grain boundary potential ba rrier. The influence of the modulated grain boundary barrier height (a t high temperature) and width (at low temperature) with different illu mination levels could explain the overall conductivity of CdTe films.