Surface-Confined Two-Dimensional Crystal Growth on a Monolayer

TL;DR

This paper introduces a chamber-free, on-chip method for growing 2D crystalline structures directly on a monolayer surface, utilizing a novel long-distance atom transport mechanism at low temperatures.

Contribution

It demonstrates a new surface-confined growth technique for 2D materials, enabling controlled synthesis of a novel 2D crystal, Pd7WTe2, without traditional vapor deposition methods.

Findings

Discovered rapid, long-distance, non-Fickian atom transport on monolayer surfaces.

Achieved controlled growth of a new 2D crystal, Pd7WTe2, at low temperatures.

Method is compatible with nanodevice fabrication and expands 2D material library.

Abstract

Conventional vapor deposition or epitaxial growth of two-dimensional (2D) materials and heterostructures is conducted in a large chamber in which masses transport from the source to the substrate. Here we report a chamber-free, on-chip approach for growing a 2D crystalline structures directly in a nanoscale surface-confined 2D space. The method is based on a surprising discovery of a rapid, long-distance, non-Fickian transport of a uniform layer of atomically thin palladium (Pd) on a monolayer crystal of tungsten ditelluride (WTe2), at temperatures well below the known melting points of all materials involved. The resulting nanoconfined growth realizes a controlled formation of a stable new 2D crystalline material, Pd7WTe2 , when the monolayer seed is either free-standing or fully encapsulated in a van der Waals stack. The approach is generalizable and highly compatible with nanodevice fabrication, promising to expand the library of 2D materials and their functionalities.