Electronic structure of GaAs–Ga1−xAlxAs quantum wires

Abstract

In this study, we report the first full scale calculation of the effect of confinement in GaAs–Ga1−xAlxAs 〈001〉 quantum wire structures. Our calculation is based on a pseudopotential scheme which has recently been applied successfully to model conventional superlattices. For thick wires our results support the infinite well approximation as far as the ground state is concerned. All confined states in thin wires (<70×70Å2) are significantly affected by additional reflections which can be identified from the charge density contour plots and tables of the momentum wave function coefficients. We find that in quantum wires the mixing of Γ and X-like momentum components is greatly diminished compared to that in conventional superlattices. We have also evaluated the oscillator strengths of the optical transitions across the forbidden gap and the conduction band nonparabolicity in the directions parallel and perpendicular to the quantum wire axis. These results are compared with the corresponding values obtained for bulk GaAs and for conventional GaAs–Ga1−xAlxAs superlattices.