High-field mobility of light holes in strained InGaAs quantum wells

Abstract

The small in-plane mass of light holes in strained quantum wells leads to high mobility at low electric fields. An analysis shows that the high-field mobility in high quality samples primarily depends on Δ, the strain splitting of the light and heavy holes, and ħω 0, the optical phonon energy. Monte Carlo calculations show that the carrier drift velocity versus electric field characteristic can be optimized for Δ ≈ ħω 0. In this case, the low field mobility is enhanced but a Gunn effect is avoided at high fields. Pulsed field measurements on a p-doped GaAs/InGaAs/GaAs sample show that the drift velocity lies below the theoretical predictions. Further calculations in which interface roughness scattering is included show that interface roughness scattering can reduce the drift velocity. Comparison with the data suggests the roughness fluctuation length Δ ≈ 10 nm.