Crystal and Electronic Structure of β‐Nb 2 N Thin Films Grown by Molecular Beam Epitaxy

作者：Jianghao Yao, Tongrui Li, Aomiao Zhi, Jianyang Ding, Rui Xu, Yuzhe Wang, Zhisheng Zhao, Zhengtai Liu, Dawei Shen, Xuezeng Tian, Xuedong Bai, Donglai Feng, Juan Jiang · 发表于：Advanced Functional Materials · 年份：2024 · DOI：10.1002/adfm.202417638 · 被引用次数：7 · 研究领域：Metal and Thin Film Mechanics、Semiconductor materials and devices、Diamond and Carbon-based Materials Research

Abstract Niobium nitrides have garnered significant research interest since their discovery due to their exceptional properties and broad applications. In this study, NbNx thin films are successfully grown on 4H(6H)‐SiC(001) substrates using nitrogen‐assisted molecular beam epitaxy. Through scanning transmission electron microscopy and X‐ray diffraction, it is confirmed that the crystal structure of the thin films corresponds to the β‐Nb 2 N. Different from the previously reported structure of the β A phase (P6 3 /mmc) of β‐Nb 2 N, the results clearly match with the β B phase (). Resistivity measurements reveal that β‐Nb 2 N exhibits superconductivity at ≈10 K with an upper critical field of ≈5 T. Its 3D electronic structure is further elucidated using angle‐resolved photoemission spectroscopy combined with theoretical calculations. The observed superconductivity in β‐Nb 2 N is attributed to its relatively high electron–phonon coupling strength and density of states at Fermi level. Interestingly, it is found that the sample is close to a Lifshitz transition, suggesting potential for tunable physical properties. The results provide a comprehensive understanding of the crystal and electronic structures of β‐Nb 2 N, facilitating its future applications.