EXCITON LIFETIMES IN GAN AND GAINN

Results from temperature dependent photoluminescence (PL) transient measurements on metalorganic vapor phase epitaxy grown epitaxial layers of GaN and GaInN are reported. In sufficiently pure GaN layers the free-exciton PL dominates even at the lowest temperatures (2 K), and the intrinsic excitonic lifetimes can be obtained. We report a value of about 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 layer sandwiched between AlN and GaInN. The PL decay time in the ternary alloy GaInN, which is dominated by localized excitons at low temperatures, is much longer, about 500 ps. (C) 1995 American Institute of Physics.