Time-resolved photoluminescence studies of carrier diffusion in GaN

The authors have studied the diffusion of carriers in GaN by photoluminescence and pump-probe spectroscopy in an InGaN/GaN single quantum well sample at 300 K. The sample was designed with the quantum well buried beneath a thick (240 nm) GaN layer. When pumping above the GaN band gap, the carriers that are excited in the GaN layer diffuse to the InGaN quantum well before recombining radiatively. The hole diffusion coefficient was determined from the rise time of the quantum well photoluminescence, together with pump-probe experiments. A value of 2.0±0.4 cm²/s is found for the diffusion coefficient.