Lennon, C., Shu, Y., Brennan, J., Namburi, D. K., Varghes, V., Hemakumara, T., Longchar, L., Srinath, S. and Hadfield, R. H. (2023) High-uniformity atomic layer deposition of superconducting niobium nitride thin films for quantum photonic integration. Materials for Quantum Technology, 3, 045401. (doi: 10.1088/2633-4356/ad0aa5)
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Abstract
Atomic layer deposition (ALD) has been identified as a promising growth method for high-uniformity superconducting thin films for superconducting quantum photonic applications, offering superior uniformity, thickness control and conformality to techniques such as reactive sputtering. The potential scalability of ALD makes this method especially appealing for fabrication of superconducting nanowires and resonators across large areas. We report on the growth of highly uniform superconducting NbN thin films via plasma-enhanced atomic layer deposition (PEALD) with radio frequency (RF) substrate biasing, on a 200 mm (8-inch) Si wafer, specifically for superconducting nanowire single-photon detector (SNSPD) applications. Niobium nitride films were grown using (tert-butylimido)-tris(diethylamido)-niobium(V) (TBTDEN) precursor and a H2/Ar plasma. The superconducting properties of a variable thickness series of films (5 – 30 nm) show critical temperature (Tc) of 13.5 K approaching bulk thickness (30 nm) with low suppression down to the ultrathin regime (5 nm) with Tc > 11 K. Tc across the 200 mm wafer with 8 nm thick NbN, measured in 15 mm intervals, exhibits minimal variation (< 7%). Microbridge structures fabricated on 8 nm thick NbN films also exhibit high critical current densities (Jc), > 10 MA/cm2 at 2.6 K. PEALD could therefore be a pivotal technique in enabling large-scale fabrication of integrated quantum photonic devices across a variety of applications.
| Item Type: | Articles |
|---|---|
| Additional Information: | RHH acknowledges support from UK Research and Innovation (UKRI) grants ST/T005920/1, EP/T00097X/1, EP/S026428/1. CTL acknowledges a PhD studentship sponsored by Oxford Instruments Plasma Technology and is supported by the EPSRC Centre for Doctoral Training in Intelligent Sensing and Measurement, grant number EP/L016753/1. |
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Brennan, Jack and Hadfield, Professor Robert and Namburi, Dr Devendra Kumar and Lennon, Ciaran |
| Authors: | Lennon, C., Shu, Y., Brennan, J., Namburi, D. K., Varghes, V., Hemakumara, T., Longchar, L., Srinath, S., and Hadfield, R. H. |
| College/School: | College of Science and Engineering > School of Engineering College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering |
| Journal Name: | Materials for Quantum Technology |
| Publisher: | IOP Publishing |
| ISSN: | 2633-4356 |
| ISSN (Online): | 2633-4356 |
| Published Online: | 08 November 2023 |
| Copyright Holders: | Copyright © 2023 The Author(s). |
| First Published: | First published in Materials for Quantum Technology 3:045401 |
| Publisher Policy: | Reproduced under a Creative Commons license |
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