Role of band offsets on the zero-field spin splitting in heterostructures

The zero-field spin properties of GaAs/Ga0.67Al0.33As quantum wells are investigated numerically through extensive self-consistent computations for selected geometries. Different mechanisms are found to contribute to the Rashba parameter α, the main ones being the conduction band offsets and the bulk spin–orbit coupling constant discontinuities at interfaces. Mismatches at the interfaces of both the normal and parallel effective masses do contribute, but are about an order of magnitude less important. Addition of a Ga0.8Al0.2As step reduces α, while in a narrow well α vanishes for some specific doping profile.