Carrier Relaxation and Exciton Bleaching in Spontaneously Ordered GaInP

Using time-resolved small-signal exciton absorption bleaching at low temperature, the optical transition energies from all three valence bands in spontaneously-ordered GaInP have been measured with high accuracy. The origin of the bleaching signal and the contributions of binding energy are discussed. With three measured energies from each sample, all parameters in the quasi-cubic perturbation model can be fitted. Good agreement is obtained with a spin-orbit splitting parameter of 103 meV, nearly independent of the degree of ordering. The ratio of bandgap reduction to crystalfield splitting parameter is found to be 2.7, slightly higher than in previous works. This difference is attributed to a more accurate determination of light-hole-like bandgap energy.