Basal-plane growth of cadmium arsenide by molecular beam epitaxy

TL;DR

This paper presents a new method for growing high-quality (001) cadmium arsenide films via molecular beam epitaxy, enabling exploration of topological phases in Dirac semimetals with improved surface morphology and electron mobility.

Contribution

It introduces a novel growth technique for (001) cadmium arsenide films using molecular beam epitaxy with a thin indium arsenide wetting layer, enhancing film quality and facilitating topological physics research.

Findings

Surface morphology and structural quality improved with indium arsenide wetting layer.

Electron mobility of 9300 cm2/Vs at 2 K in 50-nm films.

Method enables exploration of topological phases near Dirac semimetals.

Abstract

(001)-oriented thin films of the three-dimensional Dirac semimetal cadmium arsenide can realize a quantum spin Hall insulator and other kinds of topological physics, all within the flexible architecture of epitaxial heterostructures. Here, we report a method for growing (001) cadmium arsenide films using molecular beam epitaxy. The introduction of a thin indium arsenide wetting layer improves surface morphology and structural characteristics, as measured by x-ray diffraction and reflectivity, atomic force microscopy, and scanning transmission electron microscopy. The electron mobility of 50-nm-thick films is found to be 9300 cm2/Vs at 2 K, comparable to the highest-quality films grown in the conventional (112) orientation. This work demonstrates a simple experimental framework for exploring topological phases that are predicted to exist in proximity to the three-dimensional Dirac semimetal phase.