Ion mill damage in n-HgCdTe

Ion milling, a process believed to introduce interstitial mercury deeply into and type convert vacancy-doped p-HgCdTe, is shown to produce long-range isotropic damage in n-Hg1−xCdxTe (x=0.22). This damage is characterized by a bias-dependent dark current in metal–insulator semiconductor devices. Previous work has shown that ion milling also produces a moderate reduction in photoconductive response, a few micrometers below the ion-milled surface without reducing minority-carrier lifetime, and this is also presented here. It is determined that the severity of ion-mill damage can be reduced with a bake, either at 100 or 185 °C. The thermal decomposition of an anodic oxide, which is also believed to introduce interstial mercury deeply into and type convert vacancy-doped p-HgCdTe, is found to induce exactly the same changes in n-HgCdTe as obtained by ion milling. Since these two, rather different, processes both produce very deep type conversion in vacancy-doped p-HgCdTe, and also produce identical long-range electrical changes in n-HgCdTe, it is concluded that both processes share the same damage mechanism which includes the production and diffusion of interstitial mercury.