Why does wurtzite form in nanowires of III-V zinc-blende semiconductors?

TL;DR

This paper presents a nucleation-based model explaining why wurtzite forms in nanowires of zinc-blende semiconductors, highlighting the role of interface energies and growth conditions during vapor-liquid-solid synthesis.

Contribution

It introduces a model that accounts for the preferential nucleation of wurtzite at the triple phase line, clarifying the conditions favoring WZ formation over ZB in nanowire growth.

Findings

WZ nucleation occurs at the triple phase line in nanowires.

High liquid supersaturation favors WZ nucleation.

ZB forms predominantly during early growth stages.

Abstract

We develop a nucleation-based model to explain the formation of the wurtzite (WZ) crystalline phase during the vapor-liquid-solid growth of free-standing nanowires of zinc-blende (ZB) semiconductors. We first show that, in nanowires, nucleation generally occurs at the outer edge of the solid/liquid interface (the triple phase line) rather than elsewhere at the solid/liquid interface. In the present case, this entails major differences between ZB and WZ nuclei. Depending on the pertinent interface energies, WZ nucleation is favored at high liquid supersaturation. This explains our systematic observation of ZB during the early stages of nanowire growth.