Electric-field-assisted phase switching for crystal phase quantum dot fabrication in GaAs nanowires

TL;DR

This paper demonstrates electric-field-controlled crystal phase switching in GaAs nanowires during growth, enabling the precise fabrication of crystal phase quantum dots with atomically sharp interfaces for advanced optoelectronic applications.

Contribution

It introduces a novel electric-field-driven method for controlling crystal phases in GaAs nanowires during vapor-liquid-solid growth, allowing for monolayer precision in creating crystal phase quantum dots.

Findings

Electric field induces instantaneous phase switching between zinc blende and wurtzite.

Real-time TEM imaging confirms atomically sharp interfaces.

Numerical simulations elucidate the electric field's effect on catalyst droplet geometry.

Abstract

The occurrence of several crystal phases within nanostructures of a single material presents both challenges and opportunities. While unintended phase mixing can degrade optoelectronic performances, deliberate control of polytypism enables novel heterostructures with unique quantum properties, crystal phase quantum dots (CPQDs). However, since tailoring the formation of CPQDs is difficult, applications remain scarce. Here, we demonstrate electric-field-driven crystal phase switching in GaAs nanowires during vapor-liquid-solid growth, enabling precise control of crystal phases and creations of CPQDs with monolayer precision. Nanowires are epitaxially grown on custom-made silicon micro-substrates using chemical vapor deposition within an in-situ TEM. Real-time imaging reveals that the electric field switches instantaneously the crystal phase between zinc blende and wurtzite, creating atomically sharp interfaces. Numerical simulations are developed to investigate the impact of the electric field on the catalyst droplet geometry, which largely governs the crystal phase. This constitutes a key progress towards unlocking the potential of CPQDs.