Arsenic source flow rate dependence of minority carrier lifetime in GaAsN grown by chemical beam epitaxy

The tridimethylaminoarsenic (TDMAAs) flow rate dependence of minority carrier lifetime (τ_e) in GaAsN grown by chemical beam epitaxy was investigated by time-resolved-photoluminescence. It was demonstrated that with TDMAAs of more than 1.0 sccm, τ_e increases up to a nitrogen concentration of 0.6% and then stabilizes. However, it monotonically decreases with a TDMAAs of 0.5 sccm. An obvious reason of these results is the TDMAAs dependence of the density of recombination centers in GaAsN. Four electron traps, E1 to E4, localized at average energy depths of 0.05, 0.11, 0.16, and 0.39 eV, respectively below the bottom edge of the conduction band, were found to monotonically decrease in density with increasing TDMAAs. This result indeed opens interesting future for enhancing the conversion efficiency of GaAsN based solar cells.