Synthesis pathways to thin films of stable layered nitrides

TL;DR

This paper presents a synthesis pathway for creating thermodynamically stable layered nitride thin films, overcoming the challenge of metastable phase formation in vapor deposition methods, with potential applications in electronics and energy.

Contribution

It introduces a novel synthesis approach that enables the formation of stable layered ternary nitrides from elemental vapor precursors, explaining the formation of metastable intermediates.

Findings

Disordered MgMoN2 thin film acts as a metastable intermediate

Low-energy barrier enables transformation to stable layered structures

Method extends to other layered nitrides like ScTaN2, MgWN2, MgTa2N3

Abstract

Controlled synthesis of metastable materials away from equilibrium is of interest in materials chemistry. Thin film deposition methods with rapid condensation of vapor precursors can readily synthesize metastable phases, but often struggle to yield the thermodynamic ground state. Growing thermodynamically-stable structures using kinetically-limited synthesis methods in important for practical applications in electronics and energy conversion. Here, we reveal a synthesis pathway to thermodynamically-stable ordered layered ternary nitride materials, and discuss why disordered metastable intermediate phases tend to form. We show that starting from elemental vapor precursors leads to a 3D long-range disordered MgMoN2 thin film metastable intermediate structure, with a layered short-range order that has a low-energy transformation barrier to the layered 2D-like stable structure. This synthesis approach is extended to ScTaN2, MgWN2 and MgTa2N3, and may lead to the synthesis of other layered nitride thin films with unique semiconducting and quantum properties.