Direct observation of enhanced emission sites in nitrogen implanted hybrid structured ultrananocrystalline diamond films

Journal Article · Thu Feb 07 00:00:00 EST 2013 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4790481· OSTI ID:22102260

Panda, Kalpataru; Sundaravel, B.; Panigrahi, B. K. ^[1]; Chen, Huang-Chin; Lin, I. -Nan ^[2]

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1. Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India)
2. Department of Physics, Tamkang University, New-Taipei 251, Taiwan (China)

A hybrid-structured ultrananocrystalline diamond (h-UNCD) film, synthesized on Si-substrates by a two-step microwave plasma enhanced chemical vapour deposition (MPECVD) process, contains duplex structure with large diamond aggregates evenly dispersed in a matrix of ultra-small grains ({approx}5 nm). The two-step plasma synthesized h-UNCD films exhibit superior electron field emission (EFE) properties than the one-step MPECVD deposited UNCD films. Nitrogen-ion implantation/post-annealing processes further improve the EFE properties of these films. Current imaging tunnelling spectroscopy in scanning tunnelling spectroscopy mode directly shows increased density of emission sites in N implanted/post-annealed h-UNCD films than as-prepared one. X-ray photoelectron spectroscopy measurements show increased sp{sup 2} phase content and C-N bonding fraction in N ion implanted/post-annealed films. Transmission electron microscopic analysis reveals that the N implantation/post-annealing processes induce the formation of defects in the diamond grains, which decreases the band gap and increases the density of states within the band gap of diamond. Moreover, the formation of nanographitic phase surrounding the small diamond grains enhanced the conductivity at the diamond grain boundaries. Both of the phenomena enhance the EFE properties.

• OSTI ID: 22102260
• Journal Information: Journal of Applied Physics, Vol. 113, Issue 5; Other Information: (c) 2013 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANNEALING
CHEMICAL VAPOR DEPOSITION
DIAMONDS
ENERGY LEVELS
FIELD EMISSION
GRAIN BOUNDARIES
ION IMPLANTATION
MICROWAVE RADIATION
NANOSTRUCTURES
NITROGEN IONS
PLASMA
SCANNING TUNNELING MICROSCOPY
SUBSTRATES
THIN FILMS
TRANSMISSION ELECTRON MICROSCOPY
TUNNEL EFFECT
X-RAY PHOTOELECTRON SPECTROSCOPY