Fabrication of NbTiN Superconducting Nanowire Single-Photon Detectors using Helium-Focused Ion Beam

Kurschner, Matthias D.;Wolff, Martin A.;Sommer, Lisa;Lyatti, Matvey;Schuck, Carsten

Abstract

Superconducting nanowire single-photon detectors (SNSPDs) have shown to be the detector technology of choice for single photon counting experiments as they offer high repetition rate, high quantum efficiency, low time jitter and low dark count rates [1]. However, current fabrication methods employ e-beam lithography and dry etching in order to realize nanowire geometries in a top-down approach, which limits the resolution and suffers from proximity effects. In this work, we introduce state-of-the-art focused helium ion beam (HE-FIB) milling for the fabrication of niobium titanium nitride (NbTiN) nanowires. Moreover, we use automated patterning capabilities to achieve scalable fabrication of larger numbers of devices on a chip. We assess the damage nanowires may incur when exposed to helium ions and investigate the effective width and length of the manufactured nanowires. We compare results with HI-FIB milling with more established patterning techniques using a gallium FIB. We further realize long meander-shaped wires connected in series with the photosensitive nanowire for controlling the kinetic inductance, which allows realizing SNSPDs with wider nanowire width.