Unraveling the multistage phase transformations in monolayer Mo-Te compounds

TL;DR

This study systematically investigates the controllable, reversible phase transformations in monolayer Mo-Te compounds during molecular beam epitaxy, revealing insights into structural evolution and synthesis control for advanced electronic applications.

Contribution

It provides a comprehensive analysis of phase evolution in monolayer MoTe2 during growth, highlighting the effects of temperature, time, and tellurium concentration on phase control.

Findings

Identified multiple thermally driven phases including T'-MoTe2, H-MoTe2, and Mo6Te6 nanowires.

Demonstrated reversible phase transformations influenced by growth parameters.

Provided insights into synthesis and phase engineering of 2D Mo-Te materials.

Abstract

Monolayer MoTe2 exhibits a variety of derivative structural phases and associated novel electronic properties that enable a wealth of potential applications in future electronic and optoelectronic devices. However, a comprehensive study focusing on the complexities of the controllable phase evolution in this atomically thin film has yet to be performed. This work aims to address this issue by systematically investigating molecular beam epitaxial growth of monolayer Mo-Te compounds on bilayer graphene substrates. By utilizing scanning tunnelling microscopy, we explored a series of thermally driven structural phase evolutions including distinct T'-MoTe2, H-MoTe2, Mo6Te6 nanowires, and multistoichiometric MoTe2-x. Furthermore, we carefully investigated the critical effects of the growth parameters-annealing temperature and time and tellurium concentration-on the controllable and reversible phase transformation within monolayer MoTe2-x. The findings have significant implications for understanding the thin film synthesis and phase transformation engineering inherent to two-dimensional crystals, which can foster further development of high-performance devices.