Advantages of the time-resolved four-wave mixing technique for studies of non-equilibrium carrier dynamics in bulk semiconductors and structures

Abstract We demonstrate versatility of the four-wave mixing technique in investigating non-equilibrium carrier dynamics in semiconductor crystals and epitaxial structures. Measurements of the effective diffusion coefficient in the presence of a light-induced space charge field have allowed us to determine the photoconductivity type of photorefractive CdTe and InP crystals doped with deep impurities. Hole mobility values of μ h = (96 ± 22) cm 2 /Vs in CdTe and μ h = (152 ± 16) cm 2 /Vs in InP have been found from the ambipolar diffusion coefficient. Studies of a number of differently grown GaN layers with dislocation density ranging from 10 6 to 10 10 cm −2 have revealed a correlation of the longer carrier lifetimes with the smaller dislocation density. Competition between radiative and non-radiative recombination channels has been observed in low dislocation density HVPE-grown bulk-like GaN.