First-principles study of atomic and electronic structures of 60 degrees perfect and 30 degrees/90 degrees partial glide dislocations in CdTe

摘要

The atomic and electronic structures of 60 degrees glide perfect and 30 degrees/90 degrees glide partial dislocations in CdTe are studied using combined semi-empirical and density functional theory calculations. The calculations predict that the dislocation cores tend to undergo significant reconstructions along the dislocation lines from the singly-periodic (SP) structures, yielding either doubly-periodic (DP) ordering by forming a dimer or quadruply-periodic (QP) ordering by alternating a dimer and a missing dimer. Charge modulation along the dislocation line, accompanied by the QP reconstruction for the Cd-/Te-core 60 degrees perfect and 30 degrees partials or the DP reconstruction for the Cd-core 90 degrees partial, results in semiconducting character, as opposed to the metallic character of the SP dislocation cores. Dislocation-induced defect states for the 60 degrees Cd-/Te-core are located relatively close to the band edges, whereas the defect states lie in the middle of the band gap for the 30 degrees Cd-/Te-core partial dislocations. In addition to the intracore charge modulation within each QP core, the possibility of intercore charge transfer between two different dislocation cores when they are paired together in the same system is discussed. The analysis of the electronic structures reveals the potential role of the dislocations on charge transport in CdTe, particularly in terms of charge trapping and recombination.