Sources of carrier compensation in arsenic-doped HgCdTe

摘要

Using first-principles methods, we have investigated structural and electronic properties of substitutional arsenic donor (As _(Hg)), mercury vacancies (V _(Hg)), and their complexes in arsenic doping of HgCdTe. The role of V Hg in arsenic activation has also been discussed. Counterintuitively, we find that As _(Hg) and V _(Hg) is a single donor and a single acceptor, respectively. The unpaired electron of As _(Hg) makes it act as a nucleation center, driving arsenic interstitials into clusters, which is predicted as a potential candidate for arsenic deactivation. V _(Hg), exhibiting comparable formation energy with the As _(Hg) donor as well as a shallow acceptor level, is a dominant compensating acceptor in as-grown materials. Coulomb interaction allows As _(Hg) to bind at most one or two V _(Hg). The resulting complexes behave as compensating acceptors at low temperature. The model outlined for carrier compensation in arsenic-doped HgCdTe contacts well with experimental observations in arsenic activation.