QUANTUM WELL ENHANCEMENT OF NONPARABOLICITY EFFECTS ON THE EFFECTIVE ELECTRON MASS

Abstract
An analysis of the nonparabolicity effects on the subband structure in a quantum well is presented. We derive simple analytical expressions for the perpendicular mass, which describes how the confinement energies are influenced, and the parallel mass, which gives the curvature at the bottom of a subband. The anisotropy of the bulk conduction band is included and is found to have a larger effect in quantum wells than in the bulk. We find that the nonparabolicity enhancement for the parallel mass is more than three times stronger than for the perpendicular mass. An expression is also derived for the Landau levels in a perpendicular magnetic field and the cyclotron mass is found to be equal to the parallel mass in the limit B → O. We finally compare our results with recent experiments.