Optical orientation and spin-dependent recombination in GaAsN alloys under continuous-wave pumping

TL;DR

This paper develops a generalized theoretical model for spin-dependent recombination in GaAsN alloys, explaining experimental observations of optical orientation and photoluminescence polarization under continuous-wave pumping.

Contribution

It introduces a two-charge-state model with nine parameters that aligns with experimental data and derives simple equations for different pumping regimes.

Findings

Model accurately describes experimental data on GaAsN alloys.

Derived equations predict spin polarization behavior under various conditions.

Analysis of magnetic field effects on recombination and polarization.

Abstract

We present a systematic theoretical study of spin-dependent recombination and its effect on optical orientation of photoelectron spins in semiconductors with deep paramagnetic centers. For this aim we generalize the Shockley-Read theory of recombination of electrons and holes through the deep centers with allowance for optically-induced spin polarization of free and bound electrons. Starting from consideration of defects with three charge states we turn to the two-charge-state model possessing nine parameters and show that it is compatible with available experimental data on undoped GaAsN alloys. In the weak- and strong-pumping limits, we derive simple analytic equations which are useful in prediction and interpretation of experimental results. Experimental and theoretical dependencies of the spin-dependent-recombination ratio and degree of photoluminescence circular polarization on the pumping intensity and the transverse magnetic field are compared and discussed.