LOCK-IN-PHASE ANALYSIS OF N-GAAS PHOTOREFLECTANCE SPECTRA

The phase dependence of the photoreflectance signal in the region of t he E-0 transitions in GaAs samples has been investigated using the two -channel lock-in technique. The spectral components and their synchron ous phases have been established as the result of a detailed analysis of the photoreflectance spectra. The time constants of the photoreflec tance signal have been calculated for the observed single-component an d multicomponent photoreflectance spectra. The time dependence Delta R /R-j similar to+/-exp(-t/tau(j)) of the photoreflectance signal is due to the delayed reaction to the photomodulation of the electric field in the region of the semiconductor surface or interface. (C) 1998 Amer ican Institute of Physics.