Carrier lifetimes in AlGaN quantum wells: electric field and excitonic effects

Photoexcited carrier dynamics in a 280 nm AlGaN quantum well (QW) light emitting diode has been studied by time-resolved photoluminescence at forward and reverse bias. Long ( for AlGaN QWs with high Al content) room temperature carrier lifetimes of about 600 ps were measured with only a slight dependence on bias. These lifetimes are much longer than calculated free carrier tunnelling and thermionic emission times, pointing out the importance of excitonic effects for carrier dynamics in AlGaN QWs.