Carrier dynamics in GaN at extremely low excited carrier densities

Carrier dynamics in GaN was studied using fluorescence lifetime measurement in the frequency domain technique in the temperature range from 8 to 300 K at very low and very high excitation levels. The study was performed in a high-quality GaN epilayer exhibiting a room-temperature nonequilibrium carrier lifetime of 2 ns, which was determined by a light-induced transient grating (four-wave mixing) technique. The results reveal the roles of donor–acceptor pair recombination and conduction band–acceptor recombination in yellow luminescence band formation.