Optical transitions at confined resonances in (001) GaAs-Ga1−xAlxAssuperlattices

Abstract

We have performed pseudopotential calculations of the electronic structure of GaAs-${\mathrm{Ga}}_{1-x}{\mathrm{Al}}_x\mathrm{As}$ (001) square-well superlattices for $0.2<x<\mathrm{}0.5\mathrm{}$ and computed the optical matrix elements involving transitions from the top heavy-hole state to confined resonances in the conduction band. We show that such transitions are observable and demonstrate explicitly the link between the change in the Bloch component of the superlattice wave function and the change in the transition probability. Of particular interest is the range of composition 0.4-0.45 in which $\Gamma$-like and $X$-like resonances cross.