[论文解读] Synthesis of ReN3 thin films by magnetron sputtering

G. Soto, Hugo Tiznado+2 more|arXiv (Cornell University)|Nov 7, 2012

Metal and Thin Film Mechanics被引用 5

一句话总结

本研究通过在室温下采用靶材中毒的反应式磁控溅射法，实现了ReN3薄膜的合成，实现了高氮掺杂。密度泛函理论（DFT）计算证实，ReN3在正交晶系Ama2 (40)空间群中具有能量稳定性，被确认为富含氮的叠氮化物化合物，挑战了先前关于ReN2的报道，并确立了靶材中毒作为氮化物薄膜合成的可行路径。

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.

研究动机与目标

• 研究在反应式磁控溅射条件下铼氮化物相的形成行为。
• 解决关于铼-氮化合物中ReN2与ReN3组成差异的报告矛盾。
• 探索靶材中毒作为一种新型方法，用于在溅射薄膜中实现高氮含量。
• 利用XRD和DFT计算确定所得铼氮化物相的晶体结构与稳定性。

提出的方法

• 在室温下，使用氮气等离子体中的金属铼靶材进行反应式磁控溅射。
• 采用靶材中毒技术，通过在靶材和基底上同时促进化合物生成，增强氮的掺杂。
• 采用X射线衍射（XRD）分析沉积薄膜的晶体结构与相组成。
• 进行密度泛函理论（DFT）计算，评估ReN3与ReN2相的稳定性与电子结构。
• 将薄膜沉积在硅片基底上，以通过XRD实现结构表征。
• 理论分析聚焦于ReN3的正交晶系Ama2 (40)空间群，以及ReN3组成的能量偏好性。

实验结果

研究问题

• RQ1 能否通过反应式磁控溅射在薄膜形式下合成稳定的ReN3相？
• RQ2 为何报告的ReN2薄膜XRD图谱在特定取向假设下与ReN3结构一致？
• RQ3 靶材中毒是否是实现高氮含量铼氮化物薄膜的可行方法？
• RQ4 基于DFT计算，ReN3与ReN2相比的热力学稳定性如何？
• RQ5 ReN3中存在N3阴离子是否支持其被归类为富含氮的叠氮化物化合物？

主要发现

• 在假设薄膜在基底上取向的条件下，铼-氮薄膜的XRD图谱与ReN3相一致。
• 密度泛函理论计算证实，ReN3比ReN2更具能量稳定性，支持ReN3的组成。
• ReN3结晶为正交晶系Ama2 (40)空间群，表明其具有明确的晶体结构。
• 由于存在N3阴离子，该化合物被归类为叠氮化物，证实其富含氮的特性。
• 靶材中毒显著增强了氮的掺杂，即使溅射速率降低，仍能实现ReN3的形成。
• 本研究建立了一种利用中毒靶材在溅射中制备高氮含量过渡金属氮化物的新合成路径。