Sources of carrier compensation in arsenic-doped HgCdTe

Using first-principles methods, we have investigated structural and electronic properties of substitutional arsenic donor (AsHg), mercury vacancies (VHg), and their complexes in arsenic doping of HgCdTe. The role of VHg in arsenic activation has also been discussed. Counterintuitively, we find that AsHg and VHg 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. VHg, 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 VHg. 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.

► We calculated the electronic properties and stability of Hg-vacancies defects in As-doped HgCdTe. ► The Hg-vacancies defects that relate to carrier compensation in As-doped HgCdTe are confirmed. ► The role of Hg-vacancies defects in arsenic activation is discussed. ► More convinced model for arsenic doping is provided.