A Scalable Nonsuperconducting Tunnel Junction Technology

Tunnel junctions are essential for various technologies ranging from classical microelectronics to quantum information and cryogenic electronics. Aluminum and its oxide (AlOx) have long dominated cryogenic and quantum tunnel junction applications for their excellent material quality and superconductivity. However, some applications require junctions to remain normal conducting, either as standalone components or integrated with superconducting circuitry. Magnetic fields, impurity doping, or proximity effects can suppress superconductivity, but often pose challenges for scalability and integration. Here, we present a CMOS-compatible normal conducting tunnel junction platform using TiW alloy electrodes and AlOx tunnel barriers, achieving high yield and uniformity through wafer-scale fabrication. As a cryogenic use-case, the wafers incorporate junction arrays designed for Coulomb blockade thermometry, confirming reliable normal conducting state performance down to 20 mK. These results demonstrate a scalable and integrable normal conducting junction technology, supporting its use in cryogenic, quantum, and nanoelectronic systems, including hybrid superconducting-normal metal circuits.