Spin lifetimes of electrons injected into GaAs and GaN

TL;DR

This paper models electron spin relaxation times in GaAs and GaN, revealing temperature and energy dependencies, and predicts significantly longer spin lifetimes in GaN due to material properties.

Contribution

It introduces a comprehensive model using empirical pseudopotentials and accounts for multiple spin relaxation mechanisms, providing new insights into material-dependent spin lifetimes.

Findings

Spin lifetimes decrease rapidly with electron energy.

Predicted spin lifetime in GaN is about 1000 times longer than in GaAs.

Temperature dependence of spin lifetime matches experimental data in GaAs.

Abstract

The spin relaxation time of electrons in GaAs and GaN are determined with a model that includes momentum scattering by phonons and ionized impurities, and spin scattering by the Elliot-Yafet, D'yakonov-Perel, and Bir-Aronov-Pikus mechanisms. Accurate bands generated using a long-range tight-binding Hamiltonian obtained from empirical pseudopotentials are used. The inferred temperature-dependence of the spin relaxation lifetime agrees well with measured values in GaAs. We further show that the spin lifetimes decrease rapidly with injected electrons energy and reach a local maximum at the longitudinal optical phonon energy. Our calculation predicts that electron spin lifetime in pure GaN is about 3 orders of magnitude longer than in GaAs at all temperatures, primarily as a result of the lower spin-orbit interaction and higher conduction band density of states.