Chemically stabilized epitaxial wurtzite-BN thin film

TL;DR

This paper reports the successful growth of chemically stabilized epitaxial wurtzite-BN thin films on sapphire, demonstrating their promising mechanical properties for microelectronics and tooling applications.

Contribution

It introduces a novel method for stabilizing metastable w-BN epitaxial films using pulsed laser deposition and substrate effects, supported by DFT calculations.

Findings

W-BN film has hardness of 37 GPa and elastic modulus of 339 GPa.

No other BN allotropes are detected in the film.

Sapphire substrate stabilizes w-BN under specific growth conditions.

Abstract

We report on the chemically stabilized epitaxial w-BN thin film grown on c-plane sapphire by pulsed laser deposition under slow kinetic condition. Traces of no other allotropes such as cubic (c) or hexagonal (h) BN phases are present. Sapphire substrate plays a significant role in stabilizing the metastable w-BN from h-BN target under unusual PLD growth condition involving low temperature and pressure and is explained based on density functional theory calculation. The hardness and the elastic modulus of the w-BN film are 37 & 339 GPa, respectively measured by indentation along <0001> direction. The results are extremely promising in advancing the microelectronic and mechanical tooling industry.