Surface and interfaces of HgCdTe. What can we learn from 3–5’s? What is unique with HgCdTe?

Abstract

Fundamental studies of the wide variety of the surfaces and interfaces of mercury cadmium telluride are really only in their infancy. Major developments have been made in the understanding of the free surfaces of closely related 3–5 compound semiconductors and, making use of this knowledge, on the mechanism of formation of Schottky barriers and MOS (or MIS) interface states on the 3–5 materials. Thus, the 3–5 work provides an important starting point for HgCdTe work. For 3–5’s, a unified defect model has been developed which explains both the Schottky barrier formation and the source of the MOS interface states. This work is briefly reviewed and related to HgCdTe surface and interface phenomena. Based on this and a wide range of practical work plus the early results of fundamental work on HgCdTe, it is clear that defects also play an important role at HgCdTe interfaces. Previously however, it has apeared that the interface may not be so strongly coupled to defects in the bulk (i.e., to defects, dislocations, etc. in the bulk); this does not appear to be the case for HgCdTe where the ’’intercommunication’’ between the surface and bulk makes it essential to treat the surface in the context of bulk interactions and imperfections.