Confined electron states in GaAs-Ga1-xAlxAs (0.2⩽x⩽1.0) superlattices

Abstract
The authors have carried out pseudopotential calculations of the electronic structure of (001) GaAs-Ga1-xAlxAs square well superlattices of period 140 AA for 20-100% Al concentrations. They report new confined states associated with the secondary (X and L) conduction band minima and describe their behaviour as a function of x. In both cases a pattern analogous to that obtained for states derived from the centre of the Brillouin zone at Gamma is obtained. They demonstrate the effect of mixing involving momentum wavefunction contributions from the principal and secondary valleys and relate it to the choice of band offsets.