EXCITON LIFETIMES IN GAN AND GAINN

Results from temperature dependent photoluminescence (PL) transient me asurements on metalorganic vapor phase epitaxy grown epitaxial layers of GaN and GaInN are reported. In sufficiently pure GaN layers the fre e-exciton PL dominates even at the lowest temperatures (2 K), and the intrinsic excitonic lifetimes can be obtained. We report a value of ab out 125 ps for the radiative lifetime of the free exciton in GaN at 2 K, as obtained from the PL transients of a 3 mu m buried undoped GaN l ayer sandwiched between AlN and GaInN. The PL decay time in the ternar y alloy GaInN, which is dominated by localized excitons at low tempera tures, is much longer, about 500 ps. (C) 1995 American Institute of Ph ysics.