First-principles pseudopotential calculations were used to study the stability of C-related defects, and an atomic model for the H passivation of substitutional C atoms in InAs. Among the various C-related defects, the most stable one was found to be a substitutional C acceptor which occupied an As site. When compared with GaAs, substitutional C impurities were found to have higher formation energies. These were due to large lattice distortions around the C atom. Thus, the incorporation of C into bulk InAs was more difficult. Because of the small atomic radius and deep atomic energy levels of C, the defect energy level, when C occupied an In site, lay below the valence band maximum and it behaved as an acceptor. However, the formation energy was much higher than that for CAs. It was noted that an inversion between the valence band maximum and the CIn energy level occurred as the pressure was increased. For both substitutional CAs and CIn, H neutralized the electrical activity of acceptors by occupying a bond-centered site between the C atom and one of its neighbors. In the case of In0.5Ga0.5As, the C acceptor was found to favor an As site with In neighbors, and the formation energy lay between InAs and GaAs.

S.G.Lee, K.J.Chang: Physical Review B, 1996, 53[15], 9784-90