Wednesday, May 6, 2015

Cu-TiOx -TiNx NIS tunnel junction with ALD BENEQ TFS-200 TiN as Superconductor

My favourite ALD film is suddenly superconducting! Cu-TiOx -TiNx NIS tunnel junction with ALD BENEQ TFS-200 TiN as Superconductor from Department of Physics, University of Jyvaskyla,  Finland. Full manuscript available here thru the following link:

Normal-Metal–Insulator–Superconductor Tunnel Junction With Atomic-Layer-Deposited Titanium Nitride as Superconductor

Andrii Torgovkin, Saumyadip Chaudhuri, Jari Malm, Timo Sajavaara, and Ilari J. Maasilta

We report the fabrication of 70–350-nm-thick superconducting titanium nitride (TiNx) films using the atomic layer deposition (ALD) technique and the subsequent fabrication of normal metal–insulator–superconductor (NIS) tunnel junction devices from the ALD films. The films were deposited on a variety of substrates: silicon, silicon nitride, sapphire, and magnesium oxide. Superconductivity, with transition temperatures ranging from 1.35 to 1.89 K, was observed in all films. was found to depend on both the substrate type as well as film thickness. Cu-TiOx -TiNx NIS tunnel junction devices were fabricated from the TiN film deposited on silicon, using electron beam lithography and shadow angle evaporation techniques. These devices exhibit temperature-dependent current–voltage characteristics and good thermometric response from 0.1 K to slightly above . Nonlinearity in the current–voltage characteristics was observed even at temperatures as high as 5 , indicating the presence of a pseudogap in these TiNx films.