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Simultaneous diffusion of Si and Ge in isotopically controlled Si sub(1-xGe) sub(x) heterostructures

Experiments on the diffusion of Si and Ge in Si sub(1-xGe) sub(x)-isotope heterostructures with Ge contents x=0, 0.05, and 0.25 were performed at temperatures between 870 and [inline image][inline image]. The concentration profiles of the stable Si- and Ge-isotopes were recorded by means of time-of-...

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Bibliographic Details
Published in:Materials science in semiconductor processing 2008-10, Vol.11 (5-6), p.378-383
Main Authors: Kube, R, Bracht, H, Hansen, JLundsgaard, Larsen, ANylandsted, Haller, EE, Paul, S, Lerch, W
Format: Article
Language:English
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Summary:Experiments on the diffusion of Si and Ge in Si sub(1-xGe) sub(x)-isotope heterostructures with Ge contents x=0, 0.05, and 0.25 were performed at temperatures between 870 and [inline image][inline image]. The concentration profiles of the stable Si- and Ge-isotopes were recorded by means of time-of-flight secondary ion mass spectrometry. For all compositions, an Arrhenius type temperature dependence of diffusion was observed. The activation enthalpy of Si diffusion in SiGe equals the activation enthalpy of Ge diffusion and the pre-exponential factors agree within experimental accuracy. However, the absolute values of the Si and Ge diffusion coefficients indicate a clear trend. In elemental Si the diffusion coefficients of Si and Ge agree, but the difference between the diffusion coefficients of Ge and Si in Si sub(1-xGe) sub(x) increases with x. This indicates that with increasing Ge content the diffusional jumps of Ge atoms become more successful compared to that of Si. This trend is explained with an increasing contribution of vacancies to self-diffusion in Si sub(1-xGe) sub(x) with an increase of the Ge content x.
ISSN:1369-8001
DOI:10.1016/j.mssp.2008.07.005