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HL: Fachverband Halbleiterphysik

HL 61: Poster II: Materials, Interfaces and Heterostructures

HL 61.21: Poster

Donnerstag, 25. März 2010, 18:00–20:00, Poster D1

Structure and defect processes in Si_1−x−yGe_xSn_y random alloys — •U. Schwingenschlögl¹, A. Chroneos², C. Jiang³, R.W. Grimes², and H. Bracht⁴ — ¹PSE Division, KAUST, Thuwal 23955-6900, Saudi Arabia — ²Department of Materials, Imperial College London, London SW7 2BP, United Kingdom — ³Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA — ⁴Institute of Material Physics, University of Münster, Wilhelm-Klemm-Straße 10, D-48149 Münster, Germany

Binary and ternary Si_1−x−yGe_xSn_y random alloys are being considered as candidate materials to lattice match III-V or II-VI compounds with Si or Ge in optoelectronic or microelectronic devices. The simulation of the defect interactions of these alloys is hindered by their random nature. Here we use the special quasirandom approach (SQS) in conjunction with density functional theory calculations to study the structure and the defect processes. For the binary alloy Ge_xSn_1−x the SQS method correctly describes the deviation of the lattice parameters from Vegard’s Law. For the ternary alloy Si_0.375Ge_0.5Sn_0.125 we find an association of As atoms to lattice vacancies and the formation of As-vacancy pairs. It is predicted that the nearest-neighbour environment exerts a strong influence on the stability of these pairs.