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X-Ray Diffraction Studies of Annealed SiGe/Si SLS

Published online by Cambridge University Press:  22 February 2011

Walter P. Lowe ,
R. A. Macharrie  and
J. C. Bean
Walter P. Lowe
Affiliation:
AT&T Bell Laboratories, 600 Mountain Ave., Murray Hill, NJ 07974
R. A. Macharrie
Affiliation:
AT&T Bell Laboratories, 600 Mountain Ave., Murray Hill, NJ 07974
J. C. Bean
Affiliation:
AT&T Bell Laboratories, 600 Mountain Ave., Murray Hill, NJ 07974
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Abstract

We have done x-ray diffraction to study the affect of annealing on a SiGe/Si strained-layer superlattice (SLS). The post anneal spatial distribution of the Ge and Si atoms within the alloy layer is of particular interest. X-ray data taken from an annealed sample along the superlattice direction (100) show two sharp and well separated superlattice envelope functions. In contrast to the unannealed sample, and what would be a typical scattering spectra for a superlattice, the envelopes bisect the position of the unannealed sample's envelope function. The position of the envelope function is related to the tetragonal distortion εT in the SiGe alloy layers. The two separate envelopes (α and β) show that the SiGe alloy (100) planes have divided themselves into two groups with different interplanar spacings after the anneal. Each group with a tetragonal distortion such that and where εT is the tetragonal distortion in the unannealed sample. This is strong evidence for coherent phase separation perpendicular to the growth direction, along the SiGe alloy layer. In another investigation a search of reciprocal space for the 2 × 2 {… SiSiGeGe…} (111) chemically ordered state showed no evidence for the existence of such an ordered state.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 130: Symposium C – Thin Films: Stresses and Mechanical Properties I , 1988 , 205
Copyright
Copyright © Materials Research Society 1989

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