Effects of composition on field emission character of tetrahedral amorphous carbon

Kwo, Jon-Lian; Yokoyama, M.; Lin, I‐Nan

doi:10.1016/s0169-4332(98)00688-6

Cited by 9 publications

(5 citation statements)

References 8 publications

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“…With PLD, the wellknown tetrahedrally bonded amorphous carbon (ta-C) can also be produced. 19 As a basis for the discussion of our results, recent VB studies on carbon nitride films are reviewed. The aim of this work is twofold: ͑i͒ to study the effect of nitrogen supply manner, i.e., nitrogen ion beam and nitrogen gas, on the VB electronic structure of carbon nitride film; and ͑ii͒ to illustrate the influence of nitrogen content and deposition temperature on the VB electronic structure.…”

Section: Introductionmentioning

confidence: 99%

Valence band electronic structure of carbon nitride from x-ray photoelectron spectroscopy

Chen

Zhao

Yano

et al. 2002

Journal of Applied Physics

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Articles you may be interested inDeduction of the chemical state and the electronic structure of Nd2Fe14B compound from X-ray photoelectron spectroscopy core-level and valence-band spectra Hard x-ray photoemission spectroscopy in wurtzite-type zinc magnesium oxide solid-solution films grown by pulsed-laser deposition Appl. Phys. Lett. 92, 232108 (2008); 10.1063/1.2942393Fine structures of valence-band, x-ray-excited Auger electron, and plasmon energy loss spectra of diamondlike carbon films obtained using x-ray photoelectron spectroscopy

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Section: Introductionmentioning

confidence: 99%

Valence band electronic structure of carbon nitride from x-ray photoelectron spectroscopy

Chen

Zhao

Yano

et al. 2002

Journal of Applied Physics

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“…25 Since, these clusters in-turn are intercon-nected by sp 3 C, emphasizing the need of the coexistence of both the sp 3 and sp 2 bonded carbon phases (sp 3 /sp 2 ) in the material for a sustainable field emission of the nanocomposite carbon-based materials. 50 The optimum L a varies for different carbon-based materials, and had been found to fall within 0.2 and 1.2 nm. 25 The study hereby presented extends this range to 1.4 nm in order to include n-C:S ͑see Fig.…”

Section: Resultsmentioning

confidence: 97%

Investigations of the electron field emission properties and microstructure correlation in sulfur-incorporated nanocrystalline carbon thin films

Gupta

Weiner

Morell

2002

Journal of Applied Physics

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Role of sp 2 C cluster size on the field emission properties of sulfur-incorporated nanocomposite carbon thin films Appl.Results are reported on the electron field emission properties of sulfur ͑S͒-incorporated nanocrystalline carbon (n-C:S) thin films grown on molybdenum ͑Mo͒ substrates by hot-filament chemical vapor deposition ͑HFCVD͒ technique. In addition to the conventionally used methane (CH 4 ) as carbon precursor with high hydrogen (H 2 ) dilution, hydrogen sulfide-hydrogen (H 2 S)/H 2 premix gas was used for sulfur incorporation. The field emission properties for the S-incorporated films were investigated systematically as a function of substrate temperature (T S ) and sulfur concentration. Lowest turn-on field achieved was observed at around 4.0 V/m for the n-C:S sample grown at T S of 900°C with 500 ppm of H 2 S. These results are compared with those films grown without sulfur (n-C) at a particular T S . The turn-on field was found to be almost half for the S-assisted film thus demonstrating the effect of sulfur addition to the chemical vapor deposition process. An inverse relation between turn-on field (E C ), growth temperature and sulfur concentration was found. The S incorporation also causes significant microstructural changes, as characterized with non-destructive complementary ex situ techniques: scanning electron microscopy ͑SEM͒, atomic force microscopy ͑AFM͒, and Raman spectroscopy ͑RS͒. S-assisted films show relatively smoother and finer-grained surfaces than those grown without it. These findings are discussed in terms of the dual role of sulfur in enhancing the field emission properties by controlling the sp 2 C cluster size and introducing substantial structural defects through its incorporation. The in-plane correlation length (L a ) of sp 2 C cluster was determined from the intensity ratio of the Dand G-bands ͓I(D)/I(G)͔ in the visible RS as a function of deposition temperature and sulfur concentration using a phenomenological model. The turn-on field was found to decrease with increasing sp 2 C cluster size in general ranging from 0.8 to 1.4 nm. The films having sp 2 C clusters of around 1.4 nm had the lowest turn-on field and steep rising emission currents, providing an estimate of optimum size for L a for the material grown hereby. These findings are assessed in terms of a reduced field emission barrier brought about by the sulfur addition and the need for relatively longer conductive paths capable of withstanding the relatively large emission currents. It is because the sp 2 C cluster size predominate the chemical environment, chemical order, sp 3 content or local conductivity. Besides, although most of the S is expected to be electrically inactive, under the high doping conditions ͑larger S/C͒ hereby employed, there may be some amount of S in donor states, an indication of the availability of conduction electrons. These results also suggest that the behaviors of sulfur-incorporated nanocrystalline carbon thin films are closer to that grown with phosphorus ͑P͒ and Nitrogen ͑N͒ eleme...

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“…1 Since then, a-C : H film has been studied for application to fieldelectron emitters using a variety of deposition techniques, although carbon nanotubes have been considered as a possible material for a field-emission device ͑FED͒. 4,5 The turn-on field decreased from about 20 to 10 V / m when sp 3 content increased from about 70% to 85%. 3 Understanding is important for further improvement of the cathode characteristics and evaluation of their device applicability.…”

Section: Introductionmentioning

confidence: 99%

Study on the field-emission characteristics of a-C:H films

Zhang

Yao

et al. 2006

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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Articles you may be interested inEffect of oxygen plasma on field emission characteristics of single-wall carbon nanotubes grown by plasma enhanced chemical vapour deposition system J. Appl. Phys. 115, 084308 (2014); 10.1063/1.4866995Effect of high substrate bias and hydrogen and nitrogen incorporation on density of states and field-emission threshold in tetrahedral amorphous carbon films Hydrogen-contained nanoamorphous carbon films ͑a-C:H͒ were deposited on Si substrates by using microwave plasma chemical vapor deposition. A low turn-on field of 2.77 V / m was obtained. The current density of 0.28 mA/ cm 2 was obtained at an electric field of 4.8 V / m. When the electric field was increased to 6.85 V / m, the current density was dramatically decreased to 0.067 mA/ cm 2 and the bonding ratio sp 2 / sp 3 of 1.25 was decreased to 0.53. It was suggested that some of the sp 2 phase changed to sp 3 due to arc discharging and that the sp 2 phase played an important role in field emission for a-C : H films. The measurements of field emission from local emission sites of a-C : H films were carried out by using scanning tunneling microscopy. The results revealed that emission sites could be located either at the boundaries of amorphous particles or on the top of particle surface. The defected graphite model was suggested to describe the field-electron-emission characteristics of the film.

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Effects of composition on field emission character of tetrahedral amorphous carbon

Cited by 9 publications

References 8 publications

Valence band electronic structure of carbon nitride from x-ray photoelectron spectroscopy

Valence band electronic structure of carbon nitride from x-ray photoelectron spectroscopy

Investigations of the electron field emission properties and microstructure correlation in sulfur-incorporated nanocrystalline carbon thin films

Study on the field-emission characteristics of a-C:H films

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