Electronic band structure of semiconductor nanostructure arrays

Abstract

Layered, semiconductor superlattices with well widths comparable to the electron wavelength are routinely grown to tailor the electronic properties of artificially structured materials. With the recent advances in the art of nanofabrication, two-dimensional arrays of quantum nanostructures, which should exhibit three-dimensional, quantum, carrier confinement, can be made. Quantum-nanostructure arrays constitute a new generation of artificially structured materials with tailorable electronic properties. In a superlattice, zone folding of the band structure occurs only for bands along the growth direction. However, for a two-dimensional array of nanostructures, the zone folding can be tailored in two directions allowing more band mixing and the possibility of greater band alteration. We have performed augmented-plane-wave calculations for independent electrons in a two-dimensional array of two-dimensional, circular, quantum nanostructures to explore the possibilities of tailoring a two-dimensional band structure. Band structures are presented for arrays formed from different types of nanostructures: quantum boxes (wells), quantum bumps (barriers), and quantum resonators (a well surrounded by a thin barrier to allow resonant trapping in the well). Low-energy band states are quasibound in quantum-box arrays. The low-energy states channel between bumps in quantum-bump arrays. In quantum-resonator arrays, the low-energy states can be channeling states or resonant states. Useful electronic properties that can be controllably tailored are identified and discussed.