Physical Properties and Thermal Stability of Zirconium Platinum Nitride Thin Films

TL;DR

This study experimentally investigates Zr-Pt-N thin films, revealing their metastability, complex cubic phase formation, and metallic bonding properties, which differ from prior computational predictions.

Contribution

First experimental analysis of Zr-Pt-N thin films elucidating their physical properties, stability, and structural behavior, advancing understanding of ternary transition metal nitrides.

Findings

Pt substitutes nitrogen, destabilizing rock-salt structure

Pt is insoluble at 45 at %, forming a secondary phase

Films exhibit metallic bonding characteristics and metastability

Abstract

Ternary transition metal nitrides (TMNs) promise to significantly expand the material design space by opening new functionality and enhancing existing properties. However, most systems have only been investigated computationally and limited understanding of their stabilizing mechanisms restricts translation to experimental synthesis. To better elucidate key factors in designing ternary TMNs, we experimentally fabricate and analyze the physical properties of the ternary Zr-Pt-N system. Structural analysis and DFT modeling demonstrate that Pt substitutes nitrogen on the non-metallic sublattice, which destabilizes the rock-salt structure and forms a complex cubic phase. We also show insolubility of Pt in the Zr-Pt-N at 45 at % with the formation of a secondary Pt-rich phase. The measured reduced plasma frequency, decrease in resistivity, and decrease in hardness reflect a dominance of metallic behavior in bonding. Contrary to previous computational predictions, Zr-Pt-N films are shown to be metastable systems where even low Pt concentrations (1%) facilitate a solid reaction with the Si-substrate, that is inaccessible in ZrN films.