Conduction type conversion in ion etching of Au- and Ag-doped narrow-gap HgCdTe single crystal

Fundamental aspects of the p-to-n conductivity type conversion induced by ion etching in HgCdTe single crystals diffusion-doped with Au and Ag have been studied. A conversion mechanism is suggested, according to which interstitial mercury atoms rapidly diffuse from the surface source with high concentration and "kick out" impurity atoms from the cation sublattice into interstitial positions and thereby convert impurity atoms from the acceptor state to the donor state. It is shown that the structure of defects in the converted layer is unstable and the electrical parameters of this layer vary when stored at room temperature. The most probable mechanism of this process at room temperature is decomposition of an oversaturated solution of the impurity. A re-conversion to the p-type, observed in isochronous annealing of samples, is due to impurity diffusion into the converted layer from the unconverted bulk of the sample or from microscopic impurity inclusions.