Electric field effects on intersubband transitions in quantum well structures

We report on a Raman scattering study of the electric-field dependence of c₀ → c₁ intersubband transitions of electrons in a 264 Å GaAs- Al_0.3Ga_0.7As quantum-well structure. The measured Stark shifts are in very good agreement with theoretical predictions. The intensity of the intersubband peak increases rapidly with applied field due to parity-mixing. In contrast to the enhanced broadening shown by excitation resonances, the width of c₀ → c₁ is nearly independent of the field. This feature is attributed to effects of structural disorder.