Making BaZrS3 chalcogenide perovskite thin films by molecular beam epitaxy

TL;DR

This paper reports the successful synthesis of high-quality BaZrS3 thin films via molecular beam epitaxy, revealing two growth modes and establishing a foundation for chalcogenide perovskite semiconductor development.

Contribution

It introduces a novel MBE process for BaZrS3 thin films with epitaxial growth and sharp interfaces, advancing chalcogenide perovskite research.

Findings

Films are smooth and stoichiometric at the atomic level.

Two competing epitaxial growth modes identified.

Potential for strain and composition tuning in semiconductors.

Abstract

We demonstrate the making of BaZrS3 thin films by molecular beam epitaxy (MBE). BaZrS3 forms in the orthorhombic distorted-perovskite structure with corner-sharing ZrS6 octahedra. The single-step MBE process results in films smooth on the atomic scale, with near-perfect BaZrS3 stoichiometry and an atomically-sharp interface with the LaAlO3 substrate. The films grow epitaxially via two, competing growth modes: buffered epitaxy, with a self-assembled interface layer that relieves the epitaxial strain, and direct epitaxy, with rotated-cube-on-cube growth that accommodates the large lattice constant mismatch between the oxide and the sulfide perovskites. This work sets the stage for developing chalcogenide perovskites as a family of semiconductor alloys with properties that can be tuned with strain and composition in high-quality epitaxial thin films, as has been long-established for other systems including Si-Ge, III-Vs, and II-Vs. The methods demonstrated here also represent a revival of gas-source chalcogenide MBE.