Twinning superlattices in indium phosphide nanowires

TL;DR

This paper demonstrates how impurity doping, specifically zinc, can control the crystal structure of indium phosphide nanowires, enabling the formation of ordered twinning superlattices with tunable spacing based on wire diameter and zinc concentration.

Contribution

It introduces a method to induce and control twinning superlattices in InP nanowires through impurity doping, with a model explaining the periodic twinning formation.

Findings

Zinc doping promotes zinc blende over wurtzite structure.

Twinning superlattices can be tuned by wire diameter and zinc concentration.

A model explains the formation of periodic twinning based on nanowire shape.

Abstract

Here, we show that we control the crystal structure of indium phosphide (InP) nanowires by impurity dopants. We have found that zinc decreases the activation barrier for 2D nucleation growth of zinc-blende InP and therefore promotes the InP nanowires to crystallise in the zinc blende, instead of the commonly found wurtzite crystal structure. More importantly, we demonstrate that we can, by controlling the crystal structure, induce twinning superlattices with long-range order in InP nanowires. We can tune the spacing of the superlattices by the wire diameter and the zinc concentration and present a model based on the cross-sectional shape of the zinc-blende InP nanowires to quantitatively explain the formation of the periodic twinning.