Electron spin-orbit split minibands in semiconductor asymmetric superlattices -: art. no. 235305

Semiconductor superlattices can be either symmetric or asymmetric with respect to specular reflection along the growth direction. The electronic miniband structure of asymmetric superlattices is in general spin dependent, due to spin-orbit interaction. Using Kane's k.p model for the bulk and standard envelope function formalism, we have calculated the spin dependent transmission probability for electrons crossing different III-V politype multibarrier nanostructures. We have obtained spin dependent intervals of energy with nonzero transmission, corresponding to the minibands of allowed electronic states in the superlattice. Spin-orbit split minibands for InGaAs superlattices, with asymmetric double barrier unit cells and different pairs of lattice-matched barrier materials, are obtained from the transmission and reflection coefficients for the unit cell. The miniband structure is well reproduced by the transfer matrix calculation with already three unit cells. The symmetric-asymmetric crossover as well as the miniband formation from the double barrier spin split resonances were also investigated. The effect of electron spin polarization by resonant tunneling is shown to be enhanced with the use of multibarrier or superlattice structures.