Study of surface treatment effects on the metal-CdZnTe interface

The quality of a CdZnTe-based X-ray detector is highly related to the interface between semiconductor and metal contact. One of the factors that increase leakage currents in CdZnTe based X-Ray detectors is the presence of a conductive surface layer. In this paper the result of the passivation of the CdZnTe surface by means of an aqueous etching solution of NH4F/H2O2 is studied by optical ellipsometry and by the current-voltage characteristics of gold contacts deposited on the etched surface. Collected data show that leakage currents can be reduced and contact stability improved by the combined use of the passivation layer and a guard ring.