Effect of the Surface on Optical properties of AlGaAs/GaAs heterostructures with double 2-DEG

Abstract

In this work we studied a set of heterostructuresAlGaAs/GaAs by photoreflectance (PR) and photoluminescence (PL) spectroscopy in order to determine the effect of the surface on optical properties of a symmetric double two-dimensional electron gas(2DEG). The potential profiles of the edge of the conduction band were modeled by nextnano software. By Hall effect measurements at 77K we determined the electron mobility of the samples. Thesurface electric field was calculated by the analysis Franz-Keldysh oscillations observed in thePR spectra.Thecalculation of the band structure shows that the surface electric field prevents the creation of 2DEG closest to the surface. PL spectra shows a peak originated in thedeepest AlGaAs layer, close to the 2DEG region,associated with to the free exciton whose intensity increases as the electric field decrease.