Ultralarge area MOS tunnel devices for electron emission

Lasse Bjørchmar Thomsen, Gunver Nielsen, Søren Bastholm Vendelbo, Martin Johansson, Ole Hansen, Ib Chorkendorff

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Abstract

A comparative analysis of metal-oxide-semiconductor (MOS) capacitors by capacitance-voltage (C-V) and current-voltage (I-V) characteristics has been employed to characterize the thickness variations of the oxide on different length scales. Ultralarge area (1 cm(2)) ultrathin (similar to 5 nm 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. I-V 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 C-V characteristics. By plotting I-V 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 C-V characteristics on the same MOS capacitors, but are systematically lower in value. This offset between the thicknesses obtained by C-V characteristics and I-V characteristics is explained by an inherent variation of the oxide thickness. Comparison of MOS capacitors with different oxide areas ranging from 1 cm(2) to 10 mu m(2), using the slope from Fowler-Nordheim plots of the I-V characteristics as a measure of the oxide thickness, points toward two length scales of oxide thickness variations being similar to 1 cm and similar to 10 mu m, respectively.
Original languageEnglish
JournalPhysical Review B Condensed Matter
Volume76
Issue number15
Pages (from-to)155315
ISSN0163-1829
DOIs
Publication statusPublished - 2007

Bibliographical note

Copyright 2007 American Physical Society

Keywords

  • SIO2
  • FEMTOCHEMISTRY
  • THIN OXIDES
  • DESORPTION
  • SUBSTRATE DOPING LEVELS
  • SILICON DIOXIDE
  • INTERFACE OXIDATION-KINETICS
  • SURFACES
  • JUNCTIONS
  • PHYSICAL MODEL

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