Hexagonal boron nitride crystal growth in the Li3BN2-BN system

TL;DR

This paper demonstrates a novel high-temperature process for growing high-quality hexagonal boron nitride crystals from a Li3BN2-BN solution, advancing the potential for scalable 2D material applications.

Contribution

It introduces a new polymer-derived ceramics method coupled with high-temperature processing for hBN crystal growth from the Li3BN2-BN system, showing crystallization at lower temperatures.

Findings

Crystals grow by segregation from Li3BN2-BN solution upon cooling.

Crystallization can occur at temperatures as low as 1400°C.

The method is compatible with conventional flux techniques.

Abstract

Hexagonal boron nitride (hBN) presents valuable intrinsic properties and attracts considerable attention for the development of novel two-dimensional (2D) materials-based technologies. Even though huge efforts have been made to improve the bottom-up synthesis of integrated and high quality hBN, the devices presenting the best performances are still made using hBN exfoliated from bulk crystals. In this context, we explore the Polymer-Derived Ceramics (PDC) route coupled to a high temperature process that produces millimetric and high quality hBN crystals. By investigating the (micro)structure of several samples, we demonstrate that the crystal growth occurs by segregation from a Li3BN2-BN solution upon cooling and from hBN seeds. In particular, we show that crystallization can occur at a temperature as low as 1400{\textdegree}C. Overall, these results show that hBN crystal growth in the Li3BN2-BN system is compatible with conventional flux methods that may be the most promising platform for continuous seeded hBN crystal growth.