Intra-valence-band mixing in strain-compensated SiGe quantum wells

S. Tsujino, A. Borak, C. Falub, T. Fromherz, L. Diehl, H. Sigg, and D. Grützmacher
Phys. Rev. B 72, 153315 – Published 27 October 2005

Abstract

We explore the midinfrared absorption of strain-compensated pSi0.2Ge0.8Si quantum wells for various well thicknesses and temperatures. Owing to the large band offset due to the large bi-axial strain contrast between the wells and barriers, the intersubband transitions energies from the ground state to the excited heavy hole (HH), light hole (LH), and split-off (SO) hole states up to 0.5eV are resolved. When HH2 is within 30meV of LH1 or SO1 a partial transfer of the HH1-HH2 oscillator strength to the HH1-LH1 or HH1-SO1 transitions is observed, which is otherwise forbidden for light polarized perpendicular to the plane of the wells. This is a clear sign of mixing between the HH and LH or SO states. A large temperature induced broadening of HH1-HH2 transition peak is observed for narrow wells indicating nonparabolic dispersion of the HH2 states due to the mixing with the LH/SO continuum. We found that the observations are in good agreement with the six-band kp theory. A possible role of many-body effects in the temperature-induced negative peak shift is discussed.

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  • Received 6 April 2005

DOI:https://doi.org/10.1103/PhysRevB.72.153315

©2005 American Physical Society

Authors & Affiliations

S. Tsujino1,*, A. Borak1, C. Falub1, T. Fromherz2, L. Diehl1,†, H. Sigg1, and D. Grützmacher1

  • 1Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, CH-5232 Villigen-PSI, Switzerland
  • 2Institut für Halbleiter Physik und Festkörperphysik, Universität Linz, A-4040 Linz, Austria

  • *Electronic mail: soichiro.tsujino@psi.ch
  • Present address: Div. of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138.

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Issue

Vol. 72, Iss. 15 — 15 October 2005

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