p -type arsenic doping of Hg1−xCdxTe by molecular beam epitaxy

Growth of in situ As doped Hg1−xCdxTe by molecular beam epitaxy and activation of As at 250 °C is reported. We have used elemental arsenic, As4, as the p-type dopant source. The activation of As was observed in the 1016–1018 cm−3 range after a low temperature annealing step at 250 °C. However, for doping levels above 5×1018 cm−3, we have observed that the As activation efficiency drops. It is speculated at this time that self-compensation and formation of neutral As complexes may limit doping efficiency at very high levels. We also report our data on the structural and electrical characteristics of these As doped p-type layers using secondary ion mass spectroscopy analysis, and Hall effect measurements. An acceptor activation energy of 5.4 meV was obtained based on the dependence of the Hall coefficient on temperature. This value was attributed to singly ionized As located on a Te site (AsTe•) acting as an acceptor. A brief discussion on activation mechanism of As doped p-type HgCdTe material is also presented.