Numerical guidelines for setting up a general purpose k.p simulator with applications to quantum dot heterostructures and topological insulators

TL;DR

This paper provides detailed numerical guidelines for setting up a k.p Hamiltonian using finite difference methods for nanostructures, including quantum dots and topological insulators, with applications to strain effects and electronic states.

Contribution

It introduces explicit numerical procedures for constructing k.p Hamiltonians for confined nanostructures of different crystal symmetries, incorporating strain effects, and demonstrates applications to quantum dots and topological insulators.

Findings

Eigenstates of a multi-million atom InAs quantum dot computed.

Dispersion relations for Bi2Se3 topological insulator film analyzed.

Incorporation of strain fields into the k.p Hamiltonian demonstrated.

Abstract

The k.p perturbation method for determination of electronic structure first pioneered by Kohn and Luttinger continues to provide valuable insight to several band structure features. This method has been adopted to heterostructures confined up to three directions. In this paper, numerical details of setting up a k.p Hamiltonian using the finite difference approximation for such confined nanostructures is explicitly demonstrated. Nanostructures belonging to two symmetry classes namely cubic zincblende and rhombohedral crystals are considered. Rhombohedral crystals, of late, have gained prominence as candidates for the recently discovered topological insulator (TI) class of materials. Lastly the incorporation of strain field to the k.p Hamiltonian and matrix equations for computing the intrinsic and externally applied strain in heterostructures within a continuum approximation is shown. Two applications are considered 1)Computation of the eigen states of a multi-million zincblende InAs quantum dot with a stress-reducing InGaAs layer of varying Indium composition embedded in a GaAs matrix and 2)Dispersion of a rhombohedral topological insulator Bi$_{2}$Se$_{3}$ film.