EFFECT OF EPITAXIAL LAYER THICKNESS ON BUILT-IN ELECTRIC-FIELD IN REGION OF ALGAAS SI-GAAS INTERFACE - A PHOTOREFLECTANCE STUDY/

We present a study of detailed line shapes of photoreflectance spectra for Al0.3Ga0.7As/SI-GaAs epitaxial layers grown by MBE. All measureme nts were performed at 80 K under UHV conditions with a special care fo r the samples surface quality. A set of the photoreflectance spectra w as collected for photon energies close to the GaAs and Al0.3Ga0.7As ba nd gaps (E-0). The photoreflectance spectra originated in the vicinity of the Al0.3Ga0.7As/SI-GaAs interface were analyzed using the complex Airy function model of Franz-Keldysh oscillations. To examine the eff ect of the epitaxial layer thickness on parameters characterizing the interface, a step-by-step chemical etching was applied for stripping t he top layers. The built-in electric field intensity, field inhomogene ity and phenomenological broadening parameter for interface regions we re determined as a function of the epilayer thickness. PACS numbers: 7 8.66.Fd, 78.20.-e.