Selective-area van der Waals epitaxy of h-BN/graphene heterostructures via He$^{+}$ irradiation-induced defect-engineering in 2D substrates

TL;DR

This paper introduces a method for precise, selective growth of h-BN on graphene using focused He+ ion beams to create defect sites, enabling scalable and reproducible 2D heterostructure fabrication.

Contribution

It presents a novel defect-engineering approach for deterministic, selective-area van der Waals epitaxy of 2D heterostructures, improving control and scalability.

Findings

Defect sites enable targeted h-BN nucleation.

Growth quality is controlled by ion beam parameters.

h-BN layers exhibit electron tunneling similar to transferred layers.

Abstract

The combination of two-dimensional (2D) materials into heterostructures enabled the formation of atomically thin devices with designed properties. To achieve a high density, bottom-up integration, the growth of these 2D heterostructures via van der Waals epitaxy (vdWE) is an attractive alternative to the currently mostly employed mechanical transfer, which is still problematic in terms of scaling and reproducibility. However, controlling the location of the nuclei formation remains a key challenge in vdWE. Here, we use a focused He ion beam for a deterministic placement of defects in graphene substrates, which act as preferential nucleation sites for the growth of insulating, 2D hexagonal boron nitride (h-BN). We demonstrate a mask-free, selective-area vdWE (SAvdWE), where nucleation yield and crystal quality of h-BN is controlled by the ion beam parameter used for the defect formation. Moreover, we show that h-BN grown via SAvdWE has electron tunneling characteristics comparable to those of mechanically transferred layers, thereby lying the foundation for a reliable, high density array fabrication of 2D heterostructures for device integration via defect engineering in 2D substrates.