A Systematic Study of Spin-Dependent Recombination in GaAs1-xNx as a Function of Nitrogen Content

A systematic study of spin-dependent recombination (SDR) under steady-state optical pumping conditions as a function of nitrogen content, x, in dilute nitride alloys of the form GaAs1-xNx is reported. Use of high-excitation power densities up to 10(7) W cm(-2) allows measurement of the full SDR versus power curves, even at relatively high nitrogen contents of x = 0.039. Alloy contents for 0.022 <= x <= 0.039 are determined within delta x = +/- 0.005 by fitting the photoluminescence (PL) spectra using a Roosbroeck-Shockley relation, and values consistent with those obtained by studying the intensity of the GaN-like LO2 Raman mode are found. PL intensity increases by a factor known as the SDR ratio when switching from linearly to circularly polarized pump excitation. This factor reaches 5 for x = 0.022 and decreases with increasing x, falling to 1.5 for x = 0.039. Moreover, the excitation power required for maximum SDR increases with increasing x, varying from 0.6 mW for x = 0.022 to 15 mW for x = 0.039. These observations indicate an increase in the density of electronically active defects with increasing nitrogen content, both responsible for the SDR and other, standard Shockley-Read-Hall centers. The result demonstrates the importance of including nonspin-dependent recombination channels in a complete model of SDR.