Growth of Large Crystals of Janus Phase RhSeCl Using Self-Selecting Vapour Growth

TL;DR

This paper introduces a new vapour growth method for synthesizing large, high-quality Janus RhSeCl crystals, enabling advanced studies and applications in spintronics and optoelectronics.

Contribution

A novel two-step vapour growth technique for large RhSeCl crystals, with a comprehensive comparison to existing methods and impurity control strategies.

Findings

Crystals up to 6 mm in size were successfully grown.

The new method improves crystal quality and size over previous techniques.

Impurity formation can be avoided with optimized growth conditions.

Abstract

In recent years, interest in 2D Janus materials has grown exponentially, particularly with regard to their applications in spintronics and optoelectronic devices. The defining feature of Janus materials is the ordered arrangement of different layer terminations - creating chemically distinct surfaces and an inherent out-of-plane polarity. Among the few known Janus materials, RhSeCl is particularly intriguing as a rare example of an intrinsic Janus compound. Owing to its exceptional chemical stability, RhSeCl offers a promising platform for exploring the physics related to the Janus-structure. However, synthesising large, high-quality crystals of this compound remains a significant challenge. Here, we report a novel synthetic pathway for growing crystals up to 6 mm in lateral size via a two-step self-selecting vapour growth reaction. We further present a comprehensive comparison of newly developed synthesis routes with all previously reported methods for RhSeCl. During these investigations, we identified a previously unreported impurity that forms in specific growth pathways and demonstrate how it can be avoided to obtain phase-pure few- and monolayer flakes. We showcase the reproducibility of the process to obtain high-quality, large single-crystals and flakes.