Crystal‐Phase Controlled Epitaxial Growth of NbNx Superconductors on Wide‐Bandgap AlN Semiconductors
Crystal‐Phase Controlled Epitaxial Growth of NbNx Superconductors on Wide‐Bandgap AlN Semiconductors
复制标题
DOI：
10.1002/admi.202201244
复制
发表时间：
2022-09
影响因子：
5.4
通讯作者：
A. Kobayashi;Shunya Kihira;T. Takeda;Masaki Kobayashi;T. Harada;K. Ueno;H. Fujioka
中科院分区：
文献类型：
--
作者：
A. Kobayashi;Shunya Kihira;T. Takeda;Masaki Kobayashi;T. Harada;K. Ueno;H. Fujioka
NbNx和AlN之间的结构相似性有助于将超导体集成到半导体光电器件中。宽带隙AlN和超导NbNx之间的突变界面对于未来的氮化物量子器件（例如基于约瑟夫森结的量子比特）至关重要。在这项研究中，对在原子级平整的AlN/蓝宝石模板衬底上在不同温度下外延生长的NbNx的基本特性进行了研究。研究发现，随着外延生长温度的升高，在AlN上生长的NbNx薄膜的氮含量降低，导致晶体结构从δ型通过ε型和γ型转变为β型。微观结构分析表明，在高温下外延生长的NbNx薄膜结晶为纯六方β型，具有原子级平整的表面，且面内晶格常数与AlN相同。在AlN上生长具有平整界面和表面的高纯度NbNx薄膜的技术有助于氮化物半导体和超导体混合器件的集成。
The structural similarity between NbNx and AlN facilitates the integration of superconductors into semiconductor optoelectronic devices. The abrupt interface between wide‐bandgap AlN and superconducting NbNx is essential for future nitride quantum devices, such as Josephson junction‐based quantum bits. In this study, the fundamental properties of NbNx epitaxially grown at various temperatures on atomically flat AlN/sapphire template substrates are investigated. It is found that with increasing epitaxial growth temperature, the nitrogen content of NbNx films grown on AlN decreases, resulting in a change in crystal structure from δ‐ to β‐ via ε‐ and γ ‐type. Microstructural analysis reveals that NbNx thin films epitaxially grown at high temperatures crystallize into a pure hexagonal β‐type and have atomically flat surface and the same in‐plane lattice constant as AlN. The technology for growing high‐purity NbNx films with flat interfaces and surfaces on AlN can contribute to the integration of nitride semiconductors and superconductor hybrid devices.