Perspective: Mitigation of structural defects during the growth of two-dimensional van der Waals chalcogenides by molecular beam epitaxy

TL;DR

This paper presents a multi-step molecular beam epitaxy method to reduce structural defects in wafer-scale van der Waals chalcogenide thin films, enabling high-quality growth for advanced technological applications.

Contribution

It introduces a general multi-step growth procedure for high-quality, wafer-scale vdW thin films by MBE, addressing defect issues caused by weak film/substrate interactions.

Findings

Reduced defect density in vdW films using multi-step growth

Achieved high crystallinity and wafer-scale uniformity

Enhanced film quality for quantum and optoelectronic applications

Abstract

The growth of wafer-scale van der Waals (vdW) thin films and heterostructures by molecular beam epitaxy (MBE) is important for future applications in quantum technologies, next generation optoelectronic devices, and fundamental physics investigations. When grown using co-deposition methods that are typically used for compound semiconductor MBE, vdW materials typically show a high density of structural defects including twin or antiphase domains, spiral growth, and pyramidal growth. These defects are caused by the relatively weak film/substrate interaction and/or the poor wettability of typical substrates by many vdW materials. These difficulties can be mitigated using a multi-step growth procedure in which growth stages including nucleation and coalescence can be rigorously controlled, resulting in high-quality deposition of vdW thin films. This article will describe a general recipe for the growth of highly-crystalline wafer-scale vdW thin films by MBE.