Electron-optical transitions identified within the range of impurity states in E0-photoreflectance spectra of GaAs

Spectral components related to electron-optical transitions with participation of impurity states have been identified in photoreflectance spectra measured on the medium-doped crystalline GaAs substrates within the range of the E0 fundamental transition at room temperature. For their identification the phase analysis of experimental spectra as well as the spectra measurements for various density of the laser excitation were used. The dependence of the impurity component contribution and the delay phase on the density of laser excitation were determined. Experimental data treatment proved that the appearance of impurity component was strongly affected by the state of the sample surface