Analysis of Franz–Keldysh oscillations in photoreflectance spectra of a AlGaAs/GaAs single-quantum well structure

Abstract

Experimental results are presented for the physical origins of room-temperature photoreflectance features of a AlGaAs/GaAs single-quantum well structure. The spectra exhibit well-defined Franz–Keldysh oscillations which overlap with photoreflectance features due to the quantum well and complicate the determination of the energies of the transitions within the quantum well. The origin of the Franz–Keldysh oscillations are determined using wet chemical etching to selectively remove grown layers down to the substrate. The resulting spectra are presented as a function of etch depth which allows the magnitude of the built-in electric fields to be determined and reveals the location within the quantum well structure where the Franz–Keldysh oscillations originate.