# Modelling the electronic properties of GaAs polytype nanostructures: impact of strain on the conduction band character

## TL;DR

This study investigates how strain affects the electronic properties of GaAs polytype nanostructures, revealing that strain can reverse conduction band orderings and significantly influence their optical and electronic behaviors.

## Contribution

The paper provides a systematic analysis of strain effects on conduction bands in GaAs polytype nanostructures, highlighting the importance of lattice mismatch and phase composition.

## Key findings

- Strain can reverse the energy ordering of conduction bands in GaAs nanostructures.
- The energy and polarization of intersubband transitions depend on phase composition.
- Lattice mismatch induces intrinsic strain affecting electronic properties.

## Abstract

We study the electronic properties of GaAs nanowires composed of both the zincblende and wurtzite modifications using a ten-band k.p model. In the wurtzite phase, two energetically close conduction bands are of importance for the confinement and the energy levels of the electron ground state. These bands form two intersecting potential landscapes for electrons in zincblende/wurtzite nanostructures. The energy difference between the two bands depends sensitively on strain, such that even small strains can reverse the energy ordering of the two bands. This reversal may already be induced by the non-negligible lattice mismatch between the two crystal phases in polytype GaAs nanostructures, a fact that was ignored in previous studies of these structures. We present a systematic study of the influence of intrinsic and extrinsic strain on the electron ground state for both purely zincblende and wurtzite nanowires as well as for polytype superlattices. The coexistence of the two conduction bands and their opposite strain dependence results in complex electronic and optical properties of GaAs polytype nanostructures. In particular, both the energy and the polarization of the lowest intersubband transition depends on the relative fraction of the two crystal phases in the nanowire.