We have observed that a strong electric field E shifts to higher energies the photoluminescence and photocurrent peaks of a GaAs-Ga0.65Al0.35As superlattice of period D (=65 Å), which we explain by a field-induced localization of carriers to isolated quantum wells. Good agreement is found between observed and calculated shifts when the large field-induced increase of the exciton binding energy is taken into account. At moderate fields [≅(2-3)×104 V/cm], the coupling between adjacent wells is manifested by four additional peaks that shift at the rates ±eED and ±2eED and correspond to transitions that involve different levels of the Stark ladder.
E. E. Mendez, F. Agulló-Rueda, and J. M. Hong, “Stark Localization in GaAs-GaAlAs Superlattices under an Electric Field,” Phys. Rev. Lett. 60, 2426–2429 (1988). DOI: 10.1103/PhysRevLett.60.2426