Combinatorial Reactive Sputtering with Auger Parameter Analysis Enables Synthesis of Wurtzite Zn2TaN3

The discovery of new functional materials is one of thekey challengesin materials science. Combinatorial high-throughput approaches usingreactive sputtering are commonly employed to screen unexplored phasespaces. During reactive combinatorial deposition, the process conditionsare rarely optimized, which can lead to poor crystallinity of thinfilms. In addition, sputtering at shallow deposition angles can leadto off-axis preferential orientation of the grains. This can makethe results from a conventional structural phase screening ambiguous.Here, we perform a combinatorial screening of the Zn-Ta-Nphase space with the aim to synthesize the novel semiconductor Zn2TaN3. While the results of the X-ray diffraction(XRD) phase screening are inconclusive, including Auger parameteranalysis in our workflow allows us to see a very clear discontinuityin the evolution of the Ta binding environment. This is indicativeof the formation of a new ternary phase. In additional experiments,we isolate the material and perform a detailed characterization confirmingthe formation of single-phase wurtzite Zn2TaN3. Besides the formation of the new ternary nitride, we map the functionalproperties of Zn x Ta1-x N and report previously unreported clean chemicalstate analysis for Zn3N2, TaN, and Zn2TaN3. Overall, the results of this study showcase commonchallenges in high-throughput materials screening and highlight themerit of employing characterization techniques sensitive toward changesin the materials' short-range order and chemical state.