Regensburg 2010 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 36: Ge, GeSi, and Si

HL 36.2: Talk

Wednesday, March 24, 2010, 09:45–10:00, H14

Intrinsic and extrinsic diffusion of indium in germanium — •René Kube¹, Hartmut Bracht¹, Alexander Chroneos², Matthias Posselt³, and Bernd Schmidt³ — ¹Institut für Materialphysik, WWU Münster, Germany — ²Department of Materials, Imperial College, London, UK — ³Forschungszentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Dresden, Germany

Diffusion experiments with indium (In) in germanium (Ge) were performed in the temperature range between 550 and 900°C. Intrinsic and extrinsic doping levels were achieved by utilizing various implantation doses. Indium concentration profiles were recorded by means of secondary ion mass spectrometry and spreading resistance profiling. The observed concentration independent diffusion profiles are accurately described on the basis of the vacancy mechanism with a singly negatively charged mobile In-vacancy complex. In accord with the experiment, the diffusion model predicts an effective In diffusion coefficient under extrinsic conditions that is a factor of two higher than under intrinsic conditions. The temperature dependence of intrinsic In diffusion yields an activation enthalpy of 3.51 eV and confirms earlier results of Dorner et al. [Z. Metallk. 7, 325 (1982)]. The value clearly exceeds the activation enthalpy of Ge self-diffusion and indicates that the attractive interaction between In and a vacancy does not extend to third nearest neighbor sites which confirms recent theoretical calculations.