Electronic properties of nanowire superlattices in the presence of strain and magnetic-field effects

A calculation of the effective electron barrier potential in quantum-wire superlattices subject to magnetic-field and strain effects is presented. It is shown that, besides the lateral-confinement contributions to the barrier potential emphasized by the authors in earlier work (Lew Yan Voon and Willatzen 2003 J. Appl. Phys. 93 9997; Lew Yan Voon et al 2004 J. Appl. Phys. 96 4660), strong contributions from strain (lattice mismatch) may be present as well. This is due to the fact that strain values can be several percent in heterostructures while electron deformation potentials are of the order of 10 eV. It is also shown that Landau and Landé magnetic-field contributions become important at magnetic fields of 10 T or higher. The driving force behind the lateral-confinement and the Landau magnetic-field contributions is the same, namely, the electron effective-mass difference in the two material constituents forming the superlattice structure; however, the dependences of the two contributions on lateral dimensions are inverse squared and squared, respectively. Similarly, the driving force behind the Landé magnetic-field contribution, being independent of lateral dimensions, is the difference in electron g factors between the two material constituents. We note that, for InAs/GaAs nanowire superlattices, it is possible to tune the effective barrier potential around 0 for cross-sectional dimensions of 5–6 nm by use of a magnetic field. Further, since the effective barrier potential is different for spin-up and spin-down polarized electrons, magnetic-field tuning can be used to separate spin-up and spin-down electrons in quantum-wire superlattices.