Sources of carrier compensation in arsenic-doped HgCdTe

Abstract: Using first-principles methods, we have investigated structural and electronic properties of substitutional arsenic donor (AsHg), 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 AsHg and V Hg is a single donor and a single acceptor, respectively. The unpaired electron of AsHg 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 AsHg donor as well as a shallow acceptor level, is a dominant compensating acceptor in as-grown materials. Coulomb interaction allows AsHg 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. [Copyright &y& Elsevier]