Ultra-thin planar tunnel junctions grown on Nb thin films by atomic layer deposition

THIN SOLID FILMS

卷:612

Article

Zhao, Han¹  Greene, Laura H.^2,3 

[1] Univ Illinois Urban Champaign, Dept Phys, Urbana, IL 61801 USA

[2] Florida State Univ, Natl High Magnet Field Lab, Tallahassee, FL 32310 USA

[3] Florida State Univ, Dept Phys, Tallahassee, FL 32310 USA

关键词: Tunnel junction;    Ultra-thin barrier;    Atomic layer deposition;    Electronic density of states;   

DOI  :  10.1016/j.tsf.2016.06.015

来源: Elsevier

【 摘 要 】

Atomic layer deposition (ALD) is used to grow ultra-thin and low-defect Al2O3 tunnel junction barriers on sputter-deposited Nb thin films. Junctions of sizes on the order of 100 x 100 mu m(2) and barrier thicknesses of 4.4 to 11 angstrom exhibit over 90% reproducibility. The conductance characteristics at low temperature show the clear density of states signature of superconducting Nb. The junction resistance times area product increases exponentially with barrier thickness, further supporting the high quality of the junctions, in which single-step elastic tunneling predominates. The background conductance at low temperature could not be fit with the Brinkman-Dynes-Rowell model, indicating the barriers are not likely to act as a trapezoidal potential. Our work shows that ALD is an effective method in preparing planar tunnel junctions with ultra-thin barriers. (C) 2016 Elsevier B.V. All rights reserved.

【 授权许可】

Free