Microscopic origin of electrical compensation in arsenic-doped HgCdTe by molecular beam epitaxy: Density functional study

The understanding of the configurations of the arsenic tetramer (As-t), dimer (As-d and singlet (As-s) is important to explain the high electrical compensation of molecular beam epitaxy (MBE) samples and the conversion to p-type behavior. In this work, the possible configurations were optimized from density functional calculations for arsenic defects As-n (n = 1, 2, and 4) in as-grown HgTe. According to the dominant electronic contribution to the defect formation energies, which was calculated under Te-rich conditions, the most probable configurations for As-t, As-d, and As-s, have been established. The above discussion applies to the neutral arsenic defects. A further study is necessary to consider the entropy contribution to the defect formation energy.