Minority carrier diffusion length in Al sub(x)Ga sub(1-x)N (x = 0.1) grown by ammonia molecular beam epitaxy

The room-temperature minority carrier diffusion length in n -Al sub(0.1)Ga sub(0.9)N grown by ammonia molecular beam epitaxy on (0001) sapphire for photodetector applications has been investigated. The measurements were performed using the spectral dependence of the photocurrent detected by the built-in p-n -junction on thinner layer samples, and by the electron beam induced current technique on films of up to 2 mu m in thickness. The results show that the hole diffusion length in n -AlGaN films amounts to 120-150 nm, which is by 3-4 times larger than that in GaN films grown under similar growth conditions. The thicker films do not show a considerable improvement in the hole diffusion length value. ( copyright 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)