Formation Energies of Native Point Defects in Strained layer Superlattices (Postprint)
Journal Article - Open Access
Washington State University Spokane United States
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We develop a theoretical approach that employs first-principles Hamiltonian, tight-binding Hamiltonian, and Greens function techniques to obtain energy levels arising from native point defects NPDs in InAs-GaSb and InAs-InAs1-x Sb x strained layer superlattice SLS systems. In particular, we consider 4 types of NPDs anion vacancy, cation vacancy, anion anti-site, cation anti-site, isoelectronic substitution at anion sites Sb at As site and As at Sb site in the InAs, GaSb compound regions, and additional three types of defectscation at the second anion site, second anion at the cation site, and second anion vacancy in InAs1 x Sb x alloy region of the SLS. For a selected few designs, we study NPDs both in the bulk region and near the interfaces of the SLS. We have considered 12 designs of InAs-GaSb systems and 2 designs of InAs-InAs 0.7 Sb 0.3 systems lattice matched to GaSb substrate. The calculated defect levels not only agree well with available measurements but also reveal the connection between mid-gap levels and specific NPDs. We further calculate defect formation energies both in compounds and for all superlattices considered above.