Abstract
We studied the growth and oxidation of niobium nitride (NbN) films that we used to fabricate superconductive tunnel junctions. The thin films were deposited by dc reactive magnetron sputtering using a mixture of argon and nitrogen. The process parameters were optimized by monitoring the plasma with an optical spectroscopy technique. This technique allowed us to obtain NbN as well as good quality AlN films and both were used to obtain NbN/AlN/NbN trilayers. Lift-off lithography and selective anodization of the NbN films were used, respectively, to define the main trilayer geometry and/or to separate electrically, different areas of the trilayers. The anodized films were characterized by using Auger spectroscopy to analyze compounds formed on the surface and by means of a nano-indenter in order to investigate its mechanical and adhesion properties. The transport properties of NbN/AlN/NbN Josephson junctions obtained as a result of the above described fabrication process were measured in liquid helium at 4.2 K.
Highlights
Niobium (Nb) is the most commonly used material in superconducting electronics [1,2,3], but several groups have been investigating the properties of metals and alloys that could represent an alternative to it
A multilayer superconductor/insulator/ superconductor was obtained by successive depositions and patterned by means of the proposed anodization technique to obtain a Niobium nitride (NbN)/AlN/NbN Josephson junction the current–voltage characteristic of which was measured in a liquid helium bath at 4.2 K
The relative height of the Nb and N2 peaks is the parameter that we correlate to the transition temperatures of our NbN films
Summary
Niobium (Nb) is the most commonly used material in superconducting electronics [1,2,3], but several groups have been investigating the properties of metals and alloys that could represent an alternative to it. Niobium nitride (NbN), in particular, is a promising material in this respect given its relatively high critical temperature and energy gap of the order, respectively, of 16 K and 2.5 mV [4,5,6,7,8]. Several papers have been dedicated in the past to the realization of all-NbN-based superconducting tunnel junctions [9-11], but a reliable technology generating samples with quality features similar to the ones of all-Nb samples [1,12] has not emerged yet.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
