Berlin 2008 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 54: Si/Ge

HL 54.2: Vortrag

Freitag, 29. Februar 2008, 10:45–11:00, EW 202

Point defects in germanium - theory and experiment — •Sibylle Gemming, Clemens Wündisch, and Matthias Posselt — Forschungszentrum Dresden-Rossendorf, D-01314 Dresden, Germany.

The functionality of standard silicon-based semiconductor devices is achieved by careful point defect engineering, hence tremendous efforts have been made to arrive at a quantitative understanding of the underlying interactions. Germanium has distinct advantages over silicon, for instance the lower energy gap between occupied and empty electronic states and the resultant lower carrier injection barriers. However, germanium is less well studied than silicon. Thus, both theoretical and experimental investigations were carried out to study the interaction of point defects in germanium. Conductivity measurements of phosphorus-implanted germanium indicate that not all dopant atoms are electronically active. Therefore density-functional calculations were carried out to study the properties of Ge vacancies, substitutional phosphorus defects and their interaction. Stable defect clusters are obtained, and in the limit of high dopant concentration an electrically inactive form of the P dopant is predicted.