Dependence of the carrier lifetime on acceptor concentration in GaAs grown at low-temperature under different growth and annealing conditions

Using the transient reflectivity technique, we have measured the carrier lifetime in low-temperature-grown GaAs (LT-GaAs) samples as a function of growth temperature and annealing conditions. We confirm the role of the deep donor as the dominant nonradiative recombination center, but we show here that the acceptor concentration is equally crucial for the determination of the carrier lifetime as the deep donor concentration. Using the number of acceptors as the only adjustable parameter in our model, we are able to simulate the carrier lifetime for the growth and annealing conditions used in our experiments and to reproduce all the characteristics of the carrier recombination dynamics in LT-GaAs, such as nonexponential transients and the influence of the illumination intensity. The implications for the use of LT-GaAs for optoelectronic applications are discussed.