A systematic study of spin-dependent recombination in GaAs$_{1-x}$N$_x$ as a function of nitrogen content

TL;DR

This study investigates how nitrogen content affects spin-dependent recombination in GaAsN alloys, revealing that increased nitrogen reduces SDR ratio and raises excitation power needed for maximum SDR, indicating more defect centers.

Contribution

It provides a systematic analysis of SDR variation with nitrogen content in GaAsN, combining photoluminescence and Raman spectroscopy to quantify alloy composition and defect effects.

Findings

SDR ratio decreases with increasing nitrogen content

Higher nitrogen content requires more excitation power for maximum SDR

Increased nitrogen correlates with higher defect density

Abstract

A systematic study of spin-dependent recombination (SDR) under steady-state optical pumping conditions in dilute nitride semiconductors as a function of nitrogen content is reported. The alloy content is determined by a fit of the photoluminescence (PL) intensity using a Roosbroeck-Shockley relation and verified by a study of the GaN-like LO$_2$ phonon peak in a Raman spectroscopy map. PL spectra taken from alloys of the form GaAs$_{1-x}$N$_x$ where $0.022 < x < 0.036$ exhibit PL intensity increases when switching from a linearly- to a circularly-polarized pump up to a factor of 5 for $x = 0.022$. This work used a 1.39 eV laser with a radius of 0.6 $\mu$m. The observed SDR ratio monotonically decreases with increasing $x$, reaching 1.5 for $x = 0.036$. Moreover, the excitation power required to obtain maximum SDR systematically increases with increasing $x$, varying from 0.6 mW for $x = 0.022$ to 15 mW for $x = 0.036$. These observations are consistent with an increase in the density of electronically active defects with increasing nitrogen content, both those responsible for the SDR as well as other, standard Shockley-Read-Hall (SRH) centers.