Ultralarge area MOS tunnel devices for electron emission

Lasse B. Thomsen, Gunver Nielsen, Søren B. Vendelbo, Martin Johansson, Ole Hansen, and Ib Chorkendorff
Phys. Rev. B 76, 155315 – Published 23 October 2007

Abstract

A comparative analysis of metal-oxide-semiconductor (MOS) capacitors by capacitance-voltage (CV) and current-voltage (IV) characteristics has been employed to characterize the thickness variations of the oxide on different length scales. Ultralarge area (1cm2) ultrathin (5nm oxide) MOS capacitors have been fabricated to investigate their functionality and the variations in oxide thickness, with the use as future electron emission devices as the goal. IV characteristics show very low leakage current and excellent agreement to the Fowler-Nordheim expression for the current density. Oxide thicknesses have been extracted by fitting a model based on Fermi-Dirac statistics to the CV characteristics. By plotting IV characteristics in a Fowler plot, a measure of the thickness of the oxide can be extracted from the tunnel current. These apparent thicknesses show a high degree of correlation to thicknesses extracted from CV characteristics on the same MOS capacitors, but are systematically lower in value. This offset between the thicknesses obtained by CV characteristics and IV characteristics is explained by an inherent variation of the oxide thickness. Comparison of MOS capacitors with different oxide areas ranging from 1cm2to10μm2, using the slope from Fowler-Nordheim plots of the IV characteristics as a measure of the oxide thickness, points toward two length scales of oxide thickness variations being 1cm and 10μm, respectively.

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  • Received 16 May 2007

DOI:https://doi.org/10.1103/PhysRevB.76.155315

©2007 American Physical Society

Authors & Affiliations

Lasse B. Thomsen1, Gunver Nielsen1, Søren B. Vendelbo1, Martin Johansson1, Ole Hansen1,2, and Ib Chorkendorff1,*

  • 1CINF—Center for Individual Nanoparticle Functionality, Department of Physics, Nano•DTU, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
  • 2MIC—Department of Micro and Nanotechnology, Oersteds Plads Building 345E, Nano•DTU, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark

  • *ibchork@fysik.dtu.dk

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Vol. 76, Iss. 15 — 15 October 2007

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