POSSIBLE NEGATIVE-U PROPERTIES OF THE CATION VACANCY IN HGCDTE

The cation vacancy in HgCdTe is commonly used for p-type doping, but the energy levels of the vacancy acceptor are not known. We propose that the vacancy is a negative-U center, with inverted energy levels. Comparison with the vacancy in silicon,which is a well-characterized negative-U defect, indicates that the HgCdTe vacancy is likely to be a negative-U center also. The minority carrier recombination rate involving gap levels of the vacancy will show a quadratic dependence on the vacancy concentration, and the deep levels of a negative-U vacancy may be particularly suitable as recombination centers due to their location near the middle of the gap. © 1990, American Vacuum Society. All rights reserved.