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Structural Properties of Strain Symmetrized Silicon / Germanium (111) Superlattices

Published online by Cambridge University Press:  01 February 2011

C. A. Kleint ,
A. Heinrich ,
T. Muehl ,
J. Schumann  and
M. Hecker
C. A. Kleint
Affiliation:
Institute of Solid State and Materials Research Dresden, Helmholtzstr. 20, D-01069 Dresden, Germany
A. Heinrich
Affiliation:
Institute of Solid State and Materials Research Dresden, Helmholtzstr. 20, D-01069 Dresden, Germany
T. Muehl
Affiliation:
Institute of Solid State and Materials Research Dresden, Helmholtzstr. 20, D-01069 Dresden, Germany
J. Schumann
Affiliation:
Institute of Solid State and Materials Research Dresden, Helmholtzstr. 20, D-01069 Dresden, Germany
M. Hecker
Affiliation:
Institute of Solid State and Materials Research Dresden, Helmholtzstr. 20, D-01069 Dresden, Germany
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Abstract

The use of Multi Quantum Well structures has been shown to provide a promising strategy for improving the thermoelectric figure of merit. In a recent paper the concept of carrier pocket engineering has been applied to strain symmetrized Si/Ge-superlattices leading to a ZT of 0.96 at room temperature for (111) orientation. Since the strain of the individual layers is crucial for the desired modification of their band structures, their experimental determination will be of importance. We have prepared a series of (111) oriented, 100 period (Si 2nm / Ge 2nm) superlattices on a graded Si0.5Ge0.5-buffer by sputter deposition. Deposition temperature and buffer thickness have been varied, the superlattices were characterized by AFM and XRD. The technique of XRD reciprocal space mappings of asymmetric reflections has been applied to describe the strain state of the superlattice. We found a buffer thickness of 1.1μm sufficient for more than 90% strain relaxation. XRD-data of 4nm-period superlattices are consistent with complete strain symmetrization.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 626: Symposium Z – Thermoelectric Materials 2000 - The Next Generation Materials for Small-Scale Refrigeration and Power Generation Applications , 2000 , Z8.1B
Copyright
Copyright © Materials Research Society 2000

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References

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