Dataset: Momentum-resolved electronic structure and band offsets in an epitaxial NbN/GaN superconductor/semiconductor heterojunction

Tianlun Yu^1,2, John Wright³, Guru Khalsa³, Betül Pamuk⁴, Celesta S. Chang⁵, Yury Matveyev⁶, Xiaoqiang Wang¹, Thorsten Schmitt¹, Donglai Feng^7,8,9, David A. Muller^5,10, Huili Grace Xing^10,11, Debdeep Jena^10,11, Vladimir N. Strocov<sup>1

1</sup> Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.
² Advanced Materials Laboratory, State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China.
³Materials Science and Engineering, Cornell University, Ithaca, NY 14850, USA.
⁴ Platform for the Accelerated Realization, Analysis, and Discovery of Interface Materials (PARADIM), Cornell University, Ithaca, NY 14853, USA.
⁵ School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853, USA.
⁶ Photon Science, Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany.
⁷ Shanghai Research Center for Quantum Sciences, Shanghai 201315, China.
⁸ Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China.
⁹ Hefei National Laboratory for Physical Science at Microscale, CAS Center for Excellence in Quantum Information and Quantum Physics, and Department of Physics, University of Science and Technology of China, Hefei 230026, China.
¹⁰ Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY 14853, USA.
¹¹ Electrical and Computer Engineering and Materials Science and Engineering, Cornell University, Ithaca, NY 14853, USA.

The electronic structure of heterointerfaces is a pivotal factor for their device functionality. We use soft x-ray angle-resolved photoelectron spectroscopy to directly measure the momentum-resolved electronic band structures on both sides of the Schottky heterointerface formed by epitaxial films of the superconducting NbN on semiconducting GaN, and determine their momentum-dependent interfacial band offset as well as the band-bending profile. We find, in particular, that the Fermi states in NbN are well separated in energy and momentum from the states in GaN, excluding any notable electronic cross-talk of the superconducting states in NbN to GaN. We support the experimental findings with first-principles calculations for bulk NbN and GaN. The Schottky barrier height obtained from photoemission is corroborated by electronic transport and optical measurements. The momentum-resolved understanding of electronic properties of interfaces elucidated in our work opens up new frontiers for the quantum materials where interfacial states play a defining role.