STARK LOCALIZATION IN GAAS-GAALAS SUPERLATTICES UNDER A LOW ELECTRIC-FIELD

We show, from the photoluminescence of a GaAs-Ga0.65Al0.35As superlattice of period 70 Å, that the localization of the electrons takes place at low field (∼ 1 × 104 V/cm). When the localization begins, the binding energy of the heavy-hole exciton is approximately the same whether the electron wavefunction is centered on the same well as the hole or on adjacent well. The model of eigenfunctions proposed by Bleuse et al. for superlattices under electric field fits our results satisfactorily. A reduction of the electric field applied to the superlattice has been obtained by using a laser beam with photon energies greater than the bandgap width of the barriers. This effect provides accurate measurements of the low field localization. © 1991.