# 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.

## Key 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.