Stress-modulated optical spin injection in bulk Si and GaAs semiconductors

Abstract

A full band-structure ab initio calculation of the degree of spin polarization (DSP) in stressed bulk Si and bulk GaAs is reported. For Si, we found that compressive stress causes the DSP signal peak to decrease slightly in magnitude and to shift to higher energies. For expansive stress, the DSP signal shows a notable enhancement, changing from $\ensuremath{-}31.5%$ for the unstressed case to $+50%$ with only 1.5% of volumetric change. For GaAs, the only change induced due to either expansive or compressive stress is an energy shift of the DSP spectrum. This behavior may serve to tune the DSP in semiconductors to a suitable laser energy.