Exciton Absorption Bleaching Studies in Ordered GaxIn1-xP

Using time-resolved small-signal exciton absorption bleaching at low temperature as a spectroscopic technique, the optical transition energies from all three valence bands in spontaneously ordered (Formula presented)(Formula presented)P have been measured with high accuracy. The origin of the bleaching signal and the contributions of reflection, strain, and binding energy are discussed. With three measured energies from each sample, all parameters in the quasicubic 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 band-gap reduction to crystal-field-splitting parameter is found to be 2.7, slightly higher than previous works. This difference is attributed to a more accurate determination of light-hole-like band-gap energy.