Spin-dependent electron dynamics and recombination in GaAs(1-x)N(x) alloys at room temperature

TL;DR

This study investigates the spin polarization dynamics of conduction electrons in GaAs(1-x)N(x) alloys at room temperature, revealing significant circular polarization and rapid spin decay, explained by spin-dependent electron capture and a nonlinear spin dynamics model.

Contribution

It provides the first combined experimental and theoretical analysis of spin-dependent electron dynamics in GaAsN alloys at room temperature, including a nonlinear model of coupled spin systems.

Findings

Photoluminescence circular polarization reaches 40-45%.

Electron spin decays with a characteristic time of ~150 ps.

Spin-dependent capture leads to dynamical polarization of bound electrons.

Abstract

We report on both experimental and theoretical study of conduction-electron spin polarization dynamics achieved by pulsed optical pumping at room temperature in GaAs(1-x)N(x) alloys with a small nitrogen content (x = 2.1, 2.7, 3.4%). It is found that the photoluminescence circular polarization determined by the mean spin of free electrons reaches 40-45% and this giant value persists within 2 ns. Simultaneously, the total free-electron spin decays rapidly with the characteristic time ~150 ps. The results are explained by spin-dependent capture of free conduction electrons on deep paramagnetic centers resulting in dynamical polarization of bound electrons. We have developed a nonlinear theory of spin dynamics in the coupled system of spin-polarized free and localized carriers which describes the experimental dependencies, in particular, electron spin quantum beats observed in a transverse magnetic field.