Stark-ladder transition in a type-II (GaAs)8/(AlAs)8 superlattice

The Stark-ladder transitions in a type-II (GaAs)8/(AlAs)8 superlattice are investigated under various uniform electric fields by using electroreflectance spectroscopy. The electroreflectance spectra suggest the existence of a Stark-ladder transition from the heavy-hole state in the Gamma valence band to the electron state in the X conduction band. The Stark ladders of the X miniband show a strong mixing with the Gamma miniband. The experimental data from electroreflectance measurements are compared with a theoretical calculation based on the tight-binding method, and reasonable agreement is found.