Thin film TaAs: developing a platform for Weyl semimetal devices

TL;DR

This paper reports the synthesis and characterization of thin film TaAs, a Weyl semimetal, establishing a foundation for future device development by exploring growth conditions and electronic properties.

Contribution

It introduces a method for growing high-quality TaAs thin films via molecular beam epitaxy and analyzes their structural and electronic properties.

Findings

Established growth conditions for single-phase TaAs thin films.

Linked nanoscale defects to electronic structure variations.

Provided a roadmap for Weyl semimetal device development.

Abstract

MX monopnictide compounds (M=Nb,Ta, X = As,P) are prototypical three-dimensional Weyl semimetals (WSMs) that have been shown in bulk single crystal form to have potential for a wide variety of novel devices due to topologically protected band structures and high mobilities. However, very little is known about thin film synthesis, which is essential to enable device applications. We synthesize TaAs(001) epilayers by molecular beam epitaxy on GaAs(001) and provide an experimental phase diagram illustrating conditions for single phase, single-crystal-like growth. We investigate the relationship between nanoscale defects and electronic structure, using angle-resolved photoemission spectroscopy, Kelvin probe microscopy and transmission electron microscopy. Our results provide a roadmap and platform for developing 3D WSMs for device applications.