skip to main content

Title: Plasma etching of superconducting Niobium tips for scanning tunneling microscopy

We have developed a reproducible technique for the fabrication of sharp superconducting Nb tips for scanning tunneling microscopy (STM) and scanning tunneling spectroscopy. Sections of Nb wire with 250 μm diameter are dry etched in an SF₆ plasma in a Reactive Ion Etcher. The gas pressure, etching time, and applied power are chosen to control the ratio of isotropic to anisotropic etch rates and produce the desired tip shape. The resulting tips are atomically sharp, with radii of less than 100 nm, mechanically stable, and superconducting. They generate good STM images and spectroscopy on single crystal samples of Au(111), Au(100), and Nb(100), as well as a doped topological insulator Bi₂Se₃ at temperatures ranging from 30 mK to 9 K.
Authors:
 [1] ;  [2] ; ;  [1] ; ; ;  [3]
  1. Laboratory for Physical Sciences, College Park, Maryland 20740 (United States)
  2. (United States)
  3. Center for Nanophysics and Advanced Materials, Department of Physics, University of Maryland, College Park, Maryland 20742 (United States)
Publication Date:
OSTI Identifier:
22306252
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 1; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANISOTROPY; BISMUTH SELENIDES; DOPED MATERIALS; ETCHING; FABRICATION; GOLD; MOLECULAR IONS; MONOCRYSTALS; NANOWIRES; NIOBIUM; PLASMA; SCANNING TUNNELING MICROSCOPY; SPECTROSCOPY; SULFUR FLUORIDES; TEMPERATURE RANGE 0000-0013 K; TOPOLOGY; TUNNEL EFFECT