Synthesis of ReN3 thin films by magnetron sputtering

TL;DR

This paper reports the synthesis of ReN3 thin films via reactive magnetron sputtering, supported by structural analysis and density functional calculations, revealing a nitrogen-rich azide compound distinct from previously reported ReN2.

Contribution

It introduces a novel synthesis method for ReN3 thin films using target-poisoning in magnetron sputtering, and identifies the compound as ReN3 through structural and computational analysis.

Findings

ReN3 shares the same structure as ReN2 based on diffraction patterns.

Density functional calculations suggest the composition is ReN3, not ReN2.

Target-poisoning enables high nitrogen incorporation during sputtering.

Abstract

Recently was reported a novel compound between rhenium and nitrogen, announced with ReN2 composition. This compound was synthesized by the high temperature and high pressure method. We found that the diffraction peaks of this compound are in agreement with the x-ray pattern of a rhenium-nitrogen film, under the assumption that the film is oriented on the substrate. The film was prepared by reactive magnetron sputtering, at room temperature, and deposited on a silicon wafer. From the analysis of the diffractograms it could be concluded that both materials share the same structure. By density functional calculation was found that the composition could be ReN3, instead of ReN2, as stated before. The ReN3 fits in the Ama2 (40) orthorhombic space group, and by the existence of N3 anions it should be categorized as an azide; that is, a nitrogen-rich compound. To reach high nitrogen concentrations by sputtering a crucial step is the target-poisoning. Under this regime of deposition is ensured that the compound is formed simultaneously on the substrate and the target. The poisoned target is rarely used because of a reduced sputtering yield, but as shall see, it can be used as a novel synthetic technique.