First-principles calculations of vacancies related to the Shockley-Read-Hall process in MWIR and LWIR HgCdTe alloys

We studied mercury vacancy (<i>V</i>_Hg) in mercury cadmium telluride (MCT) with first-principles calculations based on density functional theory. The defect formation energies and charge transition levels (CTLs) were obtained, and their convergence with respect to the supercell size was examined. The <i>V</i>_Hg acts as a shallow acceptor in MCT with <i>x</i> = 0.21, whereas it acts as a deep acceptor, which introduces a mid-gap trap level. Picking up <i>V</i>_Cd in CdTe as a special case of MCT, i.e., <i>x</i> = 1.0 case, which also introduces an acceptor level within the band gap, we calculated the hole capture rate associated with this trap level.