Optimizing growth conditions for GaN/AlxGa1-xN multiple quantum well structures

We have investigated the optimal growth conditions for GaN/AlxGa1-xN multip le quantum well (MQW) structures by metal organic chemical vapor deposition . Optical properties of a set of GaN/AlxGa1-xN MQW samples grown under syst ematically varied growth conditions have been studied by employing picoseco nd time-resolved photoluminescence (PL) spectroscopy. The PL emission effic iency, the linewidth of the PL emission spectra, the ratio of the barrier e mission intensity to the well emission intensity, and the temperature depen dence of the PL decay lifetime of these GaN/AlxGa1-xN MQW structures have b een measured and compared with each other carefully. Based on our studies, we concluded that the optimal growth conditions for GaN/AlxGa1-xN MQW struc tures are GaN-like rather than AlxGa1-xN-like or other conditions. The GaN/ AlxGa1-xN MQW structures grown under the GaN-like growth conditions exhibit ed higher quantum efficiencies and narrower PL emission linewidths than tho se grown under other conditions. PL emission from barrier regions was not o bserved in the MQW structures grown under the GaN-like growth conditions, w hich is highly preferred for ultraviolet light emitter applications. (C) 20 00 American Institute of Physics. [S0003-6951(00)04107-3].