The idea is that you start with a substrate of silicon, and grow on that a layer of silicon-germanium alloy. Then you cap it with more silicon, generally. The thing is, though, that germanium has a lattice constant that is 4.17% larger than that of silicon, so the alloy either strains to match up or relaxes and dislocates. This is a pseudomorphic structure.
An alternative is to grow some alloy on a silicon substrate, and let the strain relax. This forms a virtual substrate. Then an alloy with a higher germanium content may be grown on this, with less strain than it would have if it had been grown on pure silicon. Or, pure silicon may be grown on the alloy.
LEPECVD is a great way to grow SiGe.
My own publications are listed on the research page, but there are many other review articles which you should read if you are interested in this field. Here are some:
This article may be found at http://dx.doi.org/10.1109/MCD.2005.1438752.
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This article may be found at http://link.aip.org/link/?jap/97/011101.
Copyright © 2005 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.
This article may be found at http://stacks.iop.org/0268-1242/19/R75
DOI: 10.1088/0268-1242/19/10/R02
Copyright © 2004 Institute of Physics Publishing Ltd.
This article may be found at http://stacks.iop.org/0022-3727/31/1397
DOI: 10.1088/0022-3727/31/12/003
Copyright © 1997 Institute of Physics Publishing Ltd.
This article may be found at http://dx.doi.org/10.1016/S0040-6090(98)00469-6.
Thin Solid Films via scienceserver.cilea.it.
Copyright © 1998 Elsevier Ltd.
This article may be found at http://stacks.iop.org/0268-1242/12/1515
DOI: 10.1088/0268-1242/12/12/001
Copyright © 1997 Institute of Physics Publishing Ltd.
This article may be found at http://link.aps.org/abstract/RMP/v73/p783.
DOI: 10.1103/RevModPhys.73.783
Copyright © 2001 The American Physical Society.
This article may be found at http://link.aps.org/abstract/RMP/v73/p767.
DOI: 10.1103/RevModPhys.73.767
Copyright © 2001 The American Physical Society.
This article may be found at http://link.aps.org/abstract/RMP/v54/p437.
DOI: 10.1103/RevModPhys.54.437
Copyright © 1982 The American Physical Society.
Copyright © 2004-2006 Danny Chrastina
Last updated: 20th December 2006
Email: danny at chrastina dot net
