Effect of indium doping on the transient optical properties of GaN films

We have investigated the effects of In doping on the optical properties of GaN films grown by gas-source molecular-beam epitaxy. Time-resolved photolu minescence was carried out to study the transient optical properties of the epitaxial films. In comparison to the undoped GaN film, the spontaneous em ission lifetime was prolonged from below 20 to 70 ps by doping with In. Und er high-excitation density, stimulated emission was observed from both samp les. The threshold excitation density was found to be reduced in the In-dop ed sample. These significant improvements of the optical properties are att ributed to the effective suppression of the formation of the nonradiative r ecombination centers caused by a change of the growth kinetics induced by a small amount of In supplied during growth of the GaN films. (C) 1999 Ameri can Institute of Physics. [S0003-6951(99)00345-9].