Low-temperature activation of As in Hg 1-x Cd x Te(211) grown on Si by molecular beam epitaxy

TLDR: In this article, the authors proposed to activate arsenic as a p-type dopant at temperatures sufficiently low that they will not compromise the integrity of p-n junctions and showed that the energy barrier for As transfer from Hg to Te sites can be overcome at 250°C.

Abstract: The HgCdTe infrared detectors and test structures based on dual or multicolor HgCdTe are desirable for various applications. It is important to control both pand n-type extrinsic doping in these photovoltaic structures. This paper addresses the issue of activating arsenic as a p-type dopant at temperatures sufficiently low that they will not compromise the integrity of p-n junctions. Midwavelength infrared (MWIR) HgCdTe epilayers were grown by molecular beam epitaxy (MBE) using an In-free type of mounting. The doping was performed by coevaporating arsenic from an elemental solid source during the growth. During postgrowth treatments, we employed a two-step annealing process. During both steps, we used temperatures (300°C, 275°C, and 250°C) that are well below the current standard annealing temperatures. The results suggest that the energy barrier for As transfer from Hg to Te sites can be overcome at 250°C; hence, p doping can be achieved at the temperature of 250°C. The temperature-dependent Hall effect characteristics of the grown samples were measured by the van der Pauw technique with magnetic fields up to 0.4 T.