INTERFACE AND SURFACE SUBSIGNALS IN PHOTOREFLECTANCE SPECTRA FOR GAAS/SI-GAAS STRUCTURES

Photoreflectance spectra were measured at room temperature for energies in the vicinity of the E(0) critical point for p-type as well as n-type doped GaAs/SI-GaAs structures. Depending on the doping concentration the existence of two photoreflectance subsignals was observed; the first one arises from the surface space charge region while the second one from the interface region. The decomposition of photoreflectance spectrum into surface and interface subsignals was based on the photoreflectance measurements carried out for different wavelengths of the laser pump beam.