Resonant indirect optical absorption in germanium

Jose Menendez, Mario Noël, Joanne C. Zwinkels, David J. Lockwood

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


The optical absorption coefficient of pure Ge has been determined from high-accuracy, high-precision optical measurements at photon energies covering the spectral range between the indirect and direct gaps. The results are compared with a theoretical model that fully accounts for the resonant nature of the energy denominators that appear in perturbation-theory expansions of the absorption coefficient. The model generalizes the classic Elliott approach to indirect excitons, and leads to a predicted optical absorption that is in excellent agreement with the experimental values using just a single adjustable parameter: the average deformation potential DΓL coupling electrons at the bottom of the direct and indirect valleys in the conduction band. Remarkably, the fitted value, DΓL=4.3×108eV/cm, is in nearly perfect agreement with independent measurements and ab initio predictions of this parameter, confirming the validity of the proposed theory, which has general applicability.

Original languageEnglish (US)
Article number121201
JournalPhysical Review B
Issue number12
StatePublished - Sep 14 2017

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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