Stark Ladder Photoluminescence of X States in GaAs/AlAs Type-I Superlattices

Abstract
We report on an observation of Stark ladder photoluminescence (PL) of X states in GaAs/AlAs type-I superlattices. The PL line exhibits a linear blue shift corresponding to one half the period of the superlattice with increasing bias voltage. The PL intensity then becomes maximum when X1-Γ2 mixing occurs. Carrier sweep-out from the X states is drastically improved by the X1-Γ2 mixing. These results demonstrate that optical properties even in type-I superlattices are seriously affected by the mixing of X states with a higher Γ subband under an electric field.