Abstract
Superconducting films ranging from a few to hundreds of nanometers thickness are integral to a wide range of quantum devices. The further development of quantum technologies hinges on material advances. With its atomic-scale growth control, plasma-enhanced atomic layer deposition (PEALD) is very promising as an enabling technique for the growth of superconducting thin films. This work demonstrates high deposition rates of ∼30-60 nm/h in PEALD of superconducting NbxTi1−xN films through a supercycle process with accurate composition control. The film thicknesses vary from 4 to 97 nm. All prepared films are face-centered cubic polycrystalline with low ∼1 at. % O content. Accurate ion-energy control by means of RF substrate biasing yields an improved electrical resistivity for 30 nm Nb0.5Ti0.5N films from 497 ± 45 μΩ cm (grounded substrate) down to 184 ± 19 μΩ cm (−81 V bias) through its impact on structural properties. Substrate biasing results in an increase in film disorder while enhancing mass density. A 6-7 K critical temperature (Tc) of superconductivity is measured for 30 nm Nb0.5Ti0.5N films, which does not show strong variations with substrate bias. The tunability and high deposition rate of the NbxTi1−xN deposition process puts forward PEALD as a promising technique to tackle material challenges in quantum technology.
| Original language | English |
|---|---|
| Article number | 026801 |
| Number of pages | 9 |
| Journal | AVS Quantum Science |
| Volume | 7 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - Jun 2025 |
Bibliographical note
Publisher Copyright:© 2025 Author(s).
Funding
This work has been carried out within the Open Technology Program with Project No. 19438, which is financed by the Netherlands Organization for Scientific Research (NWO). The authors gratefully acknowledge Arpita Saha (OIPT) for additional film depositions; Dr. Wim Arnold Bik (Detect99) for performing the RBS measurements; the Henry Royce Institute at the University of Sheffield for performing the SQUID measurements; Caspar van Bommel, Janneke Zeebregts, Barathi Krishnamoorthy for technical support at TU/e; and Cristian van Helvoirt (TU/e) for FIB preparation of TEM samples. Solliance and the Dutch province of Noord-Brabant are acknowledged for funding the TEM facility. The authors are thankful to Dr. Guillaume Krieger, Dr. Nicholas Chittock, Arthur de Jong, Sanne Deijkers, Ren\u00E9e van Limpt, and Boris de Bruin for insightful discussion and Dr. Roel Theeuwes for providing the schematic of Fig. 1. This work has been carried out within the Open Technology Program with Project No. 19438, which is financed by the Netherlands Organization for Scientific Research (NWO). The authors gratefully acknowledge Arpita Saha (OIPT) for additional film depositions; Dr. Wim Arnold Bik (Detect99) for performing the RBS measurements; the Henry Royce Institute at the University of Sheffield for performing the SQUID measurements; Caspar van Bommel, Janneke Zeebregts, Barathi Krishnamoorthy for technical support at TU/e; and Cristian van Helvoirt (TU/e) for FIB preparation of TEM samples. Solliance and the Dutch province of Noord-Brabant are acknowledged for funding the TEM facility. The authors are thankful to Dr. Guillaume Krieger, Dr. Nicholas Chittock, Arthur de Jong, Sanne Deijkers, Ren\u00E9e van Limpt, and Boris de Bruin for insightful discussion and Dr. Roel Theeuwes for providing the schematic of . Robert Hadfield acknowledges support from the UK Engineering & Physical Sciences Research Council (EPSRC\u2014Project Nos. EP/W032627/1, EP/S026428/1, and EP/T00097X/1) and the UK Science and Technologies Facilities Council (STFC\u2014Project No. ST/T005920/1). Nidhi Choudhary thanks the University of Glasgow for support through the Mary Gibb postgraduate research scholarship and access to the James Watt Nanofabrication Centre.