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Title: Structural modification of nanocrystalline diamond films via positive/negative bias enhanced nucleation and growth processes for improving their electron field emission properties

Electron field emission (EFE) properties of nanocrystalline diamond (NCD) films synthesized by the bias-enhanced growth (beg) process under different bias voltages were investigated. The induction of the nanographitic phases is presumed to be the prime factor in enhancing the EFE properties of negative biased NCD films. Transmission electron microscopic investigations reveal that a negative bias voltage of −300 V increases the rate of growth for NCD films with the size of the grains changing from nano to ultranano size. This effect also is accompanied by the induction of nanographitic filaments in the grain boundaries of the films. The turn-on field (E{sub 0}) for the EFE process then effectively gets reduced. The EFE process of the beg-NCD{sub −300V} films can be turned on at E{sub 0} = 3.86 V/μm, and the EFE current density achieved is 1.49 mA/cm{sup 2} at an applied field of 7.85 V/μm. On the other hand, though a positive-bias beg process (+200 V) results in the reduction of grain size, it does not induce sufficient nanographitic phases to lower the E{sub 0} value of the EFE process. Moreover, the optical emission spectroscopic investigation indicates that one of the primary causes that changes the granular structure of the NCD films is the increase in themore » proportion of C{sub 2} and CH species induced in the growing plasma. The polarity of the bias voltage is of less importance in the microstructural evolution of the films.« less
Authors:
;  [1] ; ;  [2] ;  [1] ;  [3] ; ;  [4]
  1. Graduate Institute of Electro-Optical Engineering and Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan (China)
  2. Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China)
  3. (United States)
  4. Department of Physics, Tamkang University, Tamsui 251, Taiwan (China)
Publication Date:
OSTI Identifier:
22412893
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 21; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CRYSTALS; CURRENT DENSITY; DIAMONDS; ELECTRIC POTENTIAL; ELECTRONS; FIELD EMISSION; FILAMENTS; FILMS; GRAIN BOUNDARIES; GRAIN SIZE; INDUCTION; NANOSTRUCTURES; NUCLEATION; PLASMA