Hole system heating by ultrafast interband energy transfer in optically excited Ge/SiGe quantum wells

K. Kolata, S. Imhof, N. S. Köster, S. Cecchi, D. Chrastina, G. Isella, J. E. Sipe, A. Thränhardt, and S. Chatterjee
Phys. Rev. B 85, 165312 – Published 18 April 2012

Abstract

An efficient scattering process between the electron system in the L valley and the hole system in the Γ valley in Ge/SiGe quantum wells is identified. Its dependencies on excitation energy and carrier density are analyzed using spectrally and time-resolved pump-probe experiments. This carrier scattering causes an ultrafast heating of the hole system leading to an additional bleaching signature appearing a few tens of picoseconds after the excitation. Our findings are supported by microscopic calculations of the absorption spectra for various carrier densities and temperatures based on the semiconductor Bloch equations. Additionally, this scattering mechanism explains the enhanced free carrier absorption observed in previously reported pump-probe experiments.

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  • Received 20 February 2012

DOI:https://doi.org/10.1103/PhysRevB.85.165312

©2012 American Physical Society

Authors & Affiliations

K. Kolata1, S. Imhof2, N. S. Köster1, S. Cecchi3, D. Chrastina3, G. Isella3, J. E. Sipe4, A. Thränhardt2, and S. Chatterjee1

  • 1Faculty of Physics and Materials Sciences Center, Philipps-Universität Marburg, Renthof 5, 35032 Marburg, Germany
  • 2Institut für Physik, Technische Universität Chemnitz, 09107 Chemnitz, Germany
  • 3Dipartimento di Fisica del Politecnico di Milano, L-NESS, Polo di Como, via Anzani 42, I-22100 Como, Italy
  • 4Department of Physics and Institute for Optical Sciences, University of Toronto, Toronto, Canada

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Issue

Vol. 85, Iss. 16 — 15 April 2012

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