Step-edge epitaxy for borophene growth on insulators

TL;DR

This paper introduces a novel step-edge epitaxy method for growing borophene on insulators, overcoming adhesion and nucleation barriers, enabling easier characterization and device integration of this 2D material.

Contribution

The study demonstrates a new growth strategy using step-edges on h-BN to facilitate borophene synthesis on insulators, which was previously hindered by weak adhesion and high nucleation barriers.

Findings

Step-edge epitaxy reduces nucleation barrier to 1.1 eV or less.

Enables growth of borophene with v1/9 phase on insulators.

Facilitates post-synthesis exfoliation and device integration.

Abstract

Borophene, a monoatomic layer of boron atoms, stands out among two-dimensional (2D) materials, with its versatile properties of polymorphism, metallicity, plasmonics, superconductivity, tantalizing for physics exploration and next-generation devices. Yet its phases are all synthesized on and stay bound to metal substrates, hampering both characterization and use. The growth on the inert insulator would allow post-synthesis exfoliation of borophene, but its weak adhesion to such substrate results in a very high 2D-nucleation barrier preventing clean borophene growth. This challenge can be circumvented in a devised and demonstrated here, with ab initio calculations, strategy. Naturally present 1D-defects, the step-edges on h-BN substrate surface, enable boron epitaxial assembly, reduce the nucleation dimensionality and lower the barrier by an order of magnitude (to 1.1 eV or less), yielding v1/9 phase. Weak borophene adhesion to the insulator makes it readily accessible for comprehensive property tests or transfer into the device setting.