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Strain effects and optical properties of Si1–xGex/Si superlattices

Rajakarunanayake, Y. F. and McGill, T. C. (1989) Strain effects and optical properties of Si1–xGex/Si superlattices. Journal of Vacuum Science and Technology B, 7 (4). pp. 799-803. ISSN 1071-1023. http://resolver.caltech.edu/CaltechAUTHORS:RAJjvstb89

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Abstract

We demonstrate that quasi direct band gap Si1–xGex/Si superlattices can be obtained by suitable choices of layer thicknesses. We calculate strain dependent conduction-band offsets as functions of the substrate alloy concentration, and of the epilayer alloy concentration. Optical matrix elements are computed for Si0.5Ge0.5/Si superlattices grown on Si0.75Ge0.25 buffer layers with superlattice layer thicknesses of 4 to 24 monolayers. We find that optical absorption and emission strengths can vary by three to four orders of magnitude for layer thickness variations as small as 1–2 monolayers, suggesting that layer thicknesses must be controlled to within one monolayer to obtain enhanced optical properties. Typical optical matrix elements calculated for these Si1–xGex/Si superlattices are three to four orders of magnitude larger than for bulk Si or Ge, but, are still three orders of magnitude smaller than for direct band gap materials such as GaAs.


Item Type:Article
Additional Information:© 1989 American Vacuum Society. (Received 5 April 1989; accepted 14 April 1989) This work was supported by the Advanced Research Projects Agency under Contract No. N00014-K-86-0841. We would also like to acknowledge useful discussions with E.T. Yu, R.H. Miles, and R.J. Hauenstein.
Subject Keywords:SILICON ALLOYS; GERMANIUM ALLOYS; SILICON; INTERFACES; SUPERLATTICES; LAYERED MATERIALS; THICKNESS; PHYSICAL PROPERTIES; CRYSTAL STRUCTURE; STRAINS; OPTICAL PROPERTIES; CRYSTAL GROWTH; BAND STRUCTURE
Record Number:CaltechAUTHORS:RAJjvstb89
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:RAJjvstb89
Alternative URL:http://dx.doi.org/10.1116/1.584603
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10194
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:16 Apr 2008
Last Modified:26 Dec 2012 09:57

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