NbN

R. Yan, G. Khalsa, S. Vishwanath, Y. Han, J. Wright, S. Katzer, N. Nepal, B. P. Downey, D. A. Muller, H. G. Xing, D. J. Meyer, D. Jena "GaN/NbN Epitaxial Semiconductor/Superconductor Heterostructures" Nature 555, 183-189 (2018)