Band structure of core-shell semiconductor nanowires

Abstract

We have calculated band structures for strained core-shell nanowires involving all combinations of AlN, GaN, and InN, as well as all combinations of AlP, GaP, AlAs, GaAs, InP, InAs, AlSb, GaSb, and InSb, as functions of core and shell radii. This gives 78 combinations, most of which have not been experimentally realized, and provides a quite complete overview of which interesting structures can be realized in core-shell zinc-blende III-V nanowires. Both the Γ - and the X-conduction-band minima were included in the calculations in addition to the valence-band maximum. The calculations were performed using continuum elasticity theory for the strain, eight-band strain-dependent k · p theory for the Γ -point energies, and a single-band approximation for the X-point conduction minima. All combinations of materials having type-I, type-II, and type-III (broken gap) band alignments have been identified, as well as all combinations for which one material becomes metallic due to a negative band gap. We identify structures that may support exciton crystals, excitonic superconductivity, and biomolecular detection. We have also computed the effective masses from which the confinement energy may be estimated. While graphical presentation of the results helps identify trends, all the numerical results are also available online. © 2008 The American Physical Society.