Formation energy and migration barrier of a Ge vacancy from ab initio studies

• Published in: Materials science in semiconductor processing Vol. 9; no. 4; pp. 498 - 502
• Main Authors: Pinto, H.M., Coutinho, J., Torres, V.J.B., Öberg, S., Briddon, P.R.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford Elsevier Ltd 01.08.2006; Elsevier Science
• Subjects: Applied sciences; Electronics; Exact sciences and technology; Germanium; Materials; Migration; Radiation damage; Scientific Computing; Teknisk-vetenskapliga beräkningar; Vacancy; Germanium; Vacancy; Migration; Radiation damage; Self diffusion; Relaxation; Diffusion barrier; Ab initio calculations; Hydrogenation; Cryogenic temperature; Energy barrier
• ISSN: 1369-8001; 1873-4081; 1873-4081
• DOI: 10.1016/j.mssp.2006.08.045

Here we present local density functional calculations of the formation and migration energies of a vacancy in large Ge supercells and hydrogen-terminated Ge clusters. Migration barriers for neutral ( V 0 ), negatively charged ( V - ) and double negatively charged ( V = ) vacancies were calculated by using symmetry-constrained atomic relaxations, as well as a nudged elastic band scheme. The formation energy of the neutral vacancy is estimated at 2.6 eV, whereas 0.4, 0.1 and 0.04 eV are obtained for migration barriers of V 0 , V - and V = , respectively. These figures account well for the formation kinetics of vacancy-impurity complexes in Ge at cryogenic temperatures, and are also in line with measured self-diffusion activation barriers obtained at elevated temperatures.