Substrate-field-modulated remote-van der Waals hybrid epitaxy in transition metal dichalcogenide heterostructures

TL;DR

This paper explores how to control the growth of 2D material layers for better optoelectronics by understanding how substrates and van der Waals forces influence their structure.

Contribution

The study introduces a new mechanism called 'remote-van der Waals hybrid epitaxy' for controlled vertical growth of 2D heterostructures.

Findings

Vertical overgrowth occurs in a narrow thickness window of 1–3 layers.

Substrate polarity and defect chemistry strongly influence nucleation density.

vdW coupling governs in-plane crystallographic registry for both stacking orders.

Abstract

Two-dimensional (2D) transition-metal dichalcogenide (TMDC) heterostructures are promising for next-generation optoelectronics, yet the mechanisms controlling their vertical heteroepitaxy remain poorly understood. Here, we systematically investigate metal–organic chemical vapor deposition growth of MoS2/WS2 and WS2/MoS2 vertical heterostructures across varying interlayer thicknesses (monolayer to multilayer) and substrates (Si, SiO2 and c-sapphire). We identify a substrate-field-modulated “remote–van der Waals (vdW) hybrid epitaxy” regime, in which vertical overgrowth is confined to a narrow thickness window (~ 1–3 layers), with nucleation density strongly influenced by substrate polarity and defect chemistry. High-resolution STEM reveals that, in the regions where vertical growth occurs, the in-plane crystallographic registry is primarily governed by vdW coupling to the 2D template, yielding a highly preferred single-orientation registry across the examined regions for both stacking orders. This dual-control mechanism decouples growth propensity from epitaxial alignment, providing a scalable framework for synthesizing high-quality 2D vertical heterostructures with precisely engineered interfaces.

The online version contains supplementary material available at 10.1186/s40580-026-00542-4.

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