Theory for the cyclotron resonance of holes in strained asymmetric Ge-SiGe quantum wells.

Abstract

We present calculations of hole Landau levels, cyclotron masses, and far-infrared spectra for strained asymmetric p-type Ge-${\mathrm{Si}}_{\mathit{x}}$${\mathrm{Ge}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$ quantum wells in a perpendicular magnetic field in order to interpret recent experimental results by Engelhardt et al. [Solid State Electron. 37, 949 (1994)]. Self-consistent hole subband calculations are combined with calculations of the Landau levels using a 6\ifmmode\times\else\texttimes\fi{}6 k\ensuremath{\cdot}p Hamiltonian for the topmost ${\mathrm{\ensuremath{\Gamma}}}_{8}$ and ${\mathrm{\ensuremath{\Gamma}}}_{7}$ bulk valence bands. Our results are in very good agreement with the experimental data. Taking into account the coupling to the split-off band turns out to be important. The complex spectra of hole Landau levels in strained quantum wells remind one of the well known quantum resonance spectra of bulk p-type Ge under uniaxial stress. \textcopyright{} 1996 The American Physical Society.