Selective Stark-ladder transitions in an asymmetric double-well GaAs/AlAs superlattice

Abstract

Optical transitions in a novel biperiodic GaAs/AlAs superlattice consisting of asymmetric double quantum wells have been investigated as a function of an applied electric field by photocurrent spectroscopy. Due to the existence of two different heavy-hole localized states under the applied field, two types of Stark-ladder transitions are possible in the superlattice. It is found that, among four possible indirect ladder transitions between the nearest neighbor wells, two of them have larger oscillator strengths. This selectivity of the indirect ladder transitions is rigorously explained by selective resonance coupling between the inequivalent neighboring wells because of the introduced structural asymmetry.