Photocurrent spectroscopic observation of interband transitions in GaAs-AlGaAs quantum wells under an applied high electric field

Abstract

A technique using photocurrent spectroscopy under high electric field perpendicular to the heterointerface has been applied to characterize the interband transitions in 105 Å thick GaAs/125 Å thick AlGaAs multiple quantum wells (MQWs). The spectra from MQWs under high electric fields show various clear exciton peaks corresponding to forbidden transitions from heavy- and light-hole subbands to electron subbands. From both allowed and forbidden transition peaks, we determined the interband transition energies between the two lowest electron and four highest hole subbands, and the splitting energies of these suhbands. Our data are in excellent agreement with a finite-square-well calculation using a conduction band offset of 60% of the hand gap discontinuity, a heavy-hole effective mass of 0.34. and a light-hole effective mass of 0.12.