Evidence for bias dependent barrier heights in gold-epitaxial CdTe Schottky diodes

Abstract

The forward bias and reverse bias current-voltage characteristics of some gold-epitaxial CdTe-on-InSb Schottky diodes have been measured at room temperature. Series resistance is evident in undoped material (base electron concentration ∼1014 cm−3) which has been measured and corrected for and identified as arising from the reverse biased CdTe-InSb junction. Two straight lines of differing slopes are present in the semilog plots for all the diodes, which we interpret as a bias-dependent barrier height. The two barrier heights, 0.91±0.04 eV and 0.74±0.02 eV, are well known in the Au-CdTe system, from which we conclude that two discrete states are present at the CdTe-Au interface. The occupancy of the states is determined by the applied bias, and hence the barrier height changes.