Electrolyte electroreflectance study of the band offset in a GaAs/Ga0.69Al0.31As superlattice

Abstract

Electrolyte electroreflectance measurements of the optical transition energies between the valence and conduction subbands of a high-quality GaAs/${\mathrm{Ga}}_{0.69}$ ${\mathrm{Al}}_{0.31}$As superlattice are reported for the first time. A full line-shape analysis of the entire experimental spectrum was carried out with all parameters fit simultaneously. Also, a new method is presented for the determination of the band offset of either a superlattice or an isolated quantum well. This new method, being less model dependent than the usual methods, allows one to avoid much of the substantial uncertainty associated with those methods. We find the value $Q_C$=0.77±0.07 for the conduction-band offset of the measured superlattice, which has a measured period of 96 Å and nominally equal well and barrier thicknesses.