Determination of exciton transition energies and oscillator strengths in AlGaAsGaAs multiple quantum well structures in an electric field using photocurrent spectroscopy

Abstract

Photocurrent spectroscopy of Al xGa 1−xAsGaAs multiple quantum well structures in an electric field perpendicular to the heterointerface was used to characterize exciton transition energies and oscillator strengths as a function of applied field. Excitons, some of which grow with increasing electric field, were identified for electric fields in the range of 0–4×10 4V/cm. The electric field dependence of exciton oscillator strengths and transition energies is attributed to a complicated interplay between local variation of zone center electron and hole wave function overlap and strong valence-band mixing. Excellent agreement between experiment and theory, which incorporates valence subband mixing effects, is found.