Room-temperature exciton electroabsorption in partially intermixed GaAs/AlGaAs quantum well waveguides

Abstract

Perpendicular field electroabsorption is measured for the first time in GaAs/AlGaAs quantum well (QW) structures which have been modified via partial interdiffusion of the well and barrier layers. In waveguide samples containing two GaAs QWs, the impurity‐free vacancy diffusion process is shown to allow continuously variable permanent band‐edge energy shifts of at least 40 meV while still retaining clearly resolved heavy hole and light hole exciton absorption peaks at room temperature. Furthermore, the quantum‐confined Stark effect is shown to be preserved in the partially intermixed structures, greatly expanding the range of photon energies over which such behavior can be utilized in a single epitaxially grown sample. Transmission resonance calculations are used to model the observed enhanced electric‐field‐induced broadening of exciton absorption peaks in the partially intermixed QWs due to increased carrier tunneling through the graded and lowered potential barriers.