Extraction of large valence-band energy offsets and comparison to theoretical values for strained-Si/strained-Ge type-II heterostructures on relaxed SiGe substrates

James T. Teherani, Winston Chern, Dimitri A. Antoniadis, Judy L. Hoyt, Liliana Ruiz, Christian D. Poweleit, Jose Menendez

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

Metal-oxide-semiconductor capacitors were fabricated on type-II staggered gap strained-Si/strained-Ge heterostructures epitaxially grown on relaxed SiGe substrates of various Ge fractions. Quasistatic quantum-mechanical capacitance-voltage (CV) simulations were fit to experimental CV measurements to extract the band alignment of the strained layers. The valence-band offset of the strained-Si/strained-Ge heterostructure was found to be 770, 760, and 670 meV for 35, 42, and 52% Ge in the relaxed SiGe substrate, respectively. These values are approximately 100 meV larger than the usually recommended band offsets for modeling Si/Ge structures. It is shown that the larger valence-band offsets found here are consistent with an 800-meV average valence-band offset between Si and Ge, which also explains the type-II band alignment observed in strained-Si 1-xGe x on unstrained-Si heterostructures.

Original languageEnglish (US)
Article number205308
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume85
Issue number20
DOIs
StatePublished - May 9 2012

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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