DIFFERENTIAL REFLECTANCE SPECTROSCOPY OF INGAAS/GAAS AND ALGAAS/GAAS QUANTUM-WELLS

A differential reflectance (DR) technique has been used to study InGaAs/GaAs and AlGaAs/GaAs quantum wells. DR was measured on "as-grown" layers, relying solely on the spatial variation of the quantum well parameters for the differential reflectance signal. The DR spectra of AlGaAs/GaAs and InGaAs/GaAs quantum wells exhibited sharp structures corresponding to the anticipated light and heavy hole excitons. The signal-to-noise ratio of the DR spectra was considerably better than the photoreflectance spectra measured on the same samples. We concude that DR is an effective and practical technique at room temperature for the study and characterization of semiconductor quantum wells and superlattices.