Superconducting nanowires by electron-beam-induced deposition

Abstract

Superconducting nanowires can be fabricated by decomposition of an organometallic gas using a focused beam of Ga ions. However, physical damage and unintentional doping often results from the exposure to the ion beam, motivating the search for a means to achieve similar structures with a beam of electrons instead of ions. This has so far remained an experimental challenge. We report the fabrication of superconducting tungsten nanowires by electron-beam-induced-deposition, with critical temperature of 2.0 K and critical magnetic field of 3.7 T, and compare them with superconducting wires made with ions. This work opens up new possibilities for the realization of nanoscale superconducting devices, without the requirement of an ion beam column.Comment: 5 pages, 4 figure

Focused electron beam induced deposition meets materials science

“…A different approach was followed by Andrey Fedorov's group. By em-ploying an inert carrier gas jet together with the precursor W(CO) 6 Henry and collaborators obtained in a single-step process FEBID structures with up to 95 at% of W [34]. So far resistivity values for these deposits have not been reported, but they are expected to be clearly in the metallic regime.…”

“…So far resistivity values for these deposits have not been reported, but they are expected to be clearly in the metallic regime. Interestingly, Sengupta and co-workers found that an optimized standard FEBID process using W(CO) 6 can yield deposits with resistivity values just on the metallic side of the Mott-Ioffe-Regel criterion [6]. These deposits become superconducting below 2 K (see section on superconductivity).…”

“…In addition, FEBID has more to offer with regard to ordered nano-granular metals or nano-dot lattices. Employing the precursor W(CO) 6 we fabricated ordered 2D square lattices of roughly semi-spherical and metallic W-C-O nano-islands of approximately 20 nm diameter and showed that a metal-insulator transition occurs as a function of lattice constant [94,95]. In this case, the metal-poor co-deposit around the metallic nano-islands served as tunneling matrix.…”

“…last decade FEBID or, more generally, focused electron beam induced processing (FEBIP) has developed from a rather exotic technique employed by a small number of specialist groups for a rather limited but important selection of applications, such as mask repair [4], into a highly versatile technology for various materials research areas. These comprise amorphous and polycrystalline superconductors [5,6,7], magnetic materials [8], alloys and intermetallic compounds [9,10,11,12,13,14,15], multilayer structures [15,16] and metamaterials in which suitable materials combinations result in a desired functionality [17,8]. The latter approach, in particular, has opened a new pathway to the realization of different sensor applications [18,19,20,21,22].…”

Superconductivity and metallic behavior in PbxCyOδ structures prepared by focused electron beam induced deposition

“…So far, indications of superconductivity in FEBID structures were only found in the system MoC. 18 Only recently after the submission of this manuscript, Sengupta et al discovered superconductivity in tungsten-based nanowires fabricated by FEBID with a superconducting onset temperature of 2.0 K. 19 By using optimized deposition parameters, we were able to stabilize a superconducting phase with the same T c of 7.2 K as known for bulk lead. 20 Furthermore, the as-grown structures deposited with optimized parameters exhibit metallic behavior and a resistivity of 190 lXcm at T ¼ 300 K dropping to 16 lXcm before the superconducting onset.…”