Wafer-level uniformity of atomic-layer-deposited niobium nitride thin films for quantum devices

Superconducting niobium nitride thin films are used for a variety of photon detectors, quantum devices, and superconducting electronics. Most these applications require highly uniform films, instance, when moving from single-pixel detectors to arrays with large active area. Plasma-enhanced atomic layer deposition (ALD) is feasible option produce high-quality, conformal has been demonstrated as film method fabricate nanowire single-photon before. Here, we explore the property spread ALD-NbN across 6-in. wafer Over equivalent area 2-in. wafer, measure maximum deviation 1% in critical temperature 12% switching current. Toward larger areas, structural characterizations indicate that changes crystal structure seem be limiting factor rather than composition or impurities. The results show ALD suited NbN material large-area detector new designs devices requiring precise thickness control.