COMPARISON OF THE DIFFUSION OF HG INTO CDTE AND HG0.8CD0.2TE

In this paper, results published recently on Hg diffusion in the impor tant infrared detector material, Hg0.8Cd0.2Te, and its common substrat e material, CdTe, are compared and discussed. As is customary with dif fusion studies in II-VI semiconductors, two component profiles were ob tained in the majority of cases, each profile giving two values of the diffusivity. The values of D for the mercury diffusion in CdTe were m uch less than corresponding values in Hg0.8Cd0.2Te. In Hg0.8Cd0.2Te di ffusion proceeds by volume diffusion followed by short circuit diffusi on, whereas in CdTe diffusion is rate limiting volume diffusion involv ing a slow stream and a fast stream. From pressure dependency measurem ents, it is proposed that the slow component occurs by an interstitial mechanism at low P-Hg and a vacancy mechanism at high P-Hg, whereas i n Hg0.8C0.2Te the reverse occurs for the fast diffusion component. In CdTe, the slow component increases systematically with etch pit densit y, whereas in Hg0.8Cd0.2Te, the diffusivity is independent of the qual ity of the material. From the comparisons,it is seen that there are so me common features in the diffusion of Hg in the two materials but the re are also some clear and distinct differences.