Electric-Field Emission Mechanism in Q-Carbon Field Emitters

Abstract

In this paper, we report the excellent field emission properties of Q-carbon and analyze its field emission characteristics through structural, morphological, and electronic property correlations, supported by density functional theory (DFT) simulation studies. The Q-carbon field emitters show impressive and stable field emission properties, such as a low turn-on electric field of ∼2.38 V/μm, a high emission current density of ∼33 μA/cm2, and a critical field of ∼2.44 V/μm for the transition from a linear region to the saturation region in the F–N plot. The outstanding field emission properties of Q-carbon are attributed to (i) a unique sp2/sp3 mixture in Q-carbon, (ii) sp2-bonded highly conductive amorphous carbon-rich channels inside the Q-carbon cluster, (iii) a large local field enhancement due to the local geometry and microstructure of Q-carbon, and (iv) the presence of sp2-bonded amorphous carbon regions in the composite film. The temperature-dependent field emission properties, such as extreme sensitivity and an enhancement in the emission current density with temperature, can be explained by the local density of states near the Fermi level and the excellent thermal stability of the Q-carbon field emitters. From DFT simulation studies, the computed work function and the field-enhancement factor were determined to be 3.62 eV and ∼2300, respectively, which explains the excellent field emission characteristics of Q-carbon. The obtained field emission properties, in most cases, were superior to those from other carbon/diamond-based field emitters, which will open new frontiers in field emission-based electronic applications.

Field emission from vertically oriented 2D manganese monosulfide sheets derived via a chemical route

“…Furthermore, the presence of sharp protruding active edges and localized defect sites in these nanomaterials can enhance the electron tunneling probability similar to that seen in nanotubes. 28…”

“…Furthermore, the presence of sharp protruding active edges and localized defect sites in these nanomaterials can enhance the electron tunneling probability similar to that seen in nanotubes. 28 The field emission characteristics of the synthesized Mn 3 O 4 nanoparticles and MnS nanostructure were analyzed through the F-N equation, as follows: , b is the field enhancement factor, E is the external applied electric field, j is the work function of the cathode, A is the effective emission area, and v F and t F are the values of the special elliptical function v and t, respectively. 29 The Fowler-Nordheim theory is used to calculate the local current density J at some point on the emitting surface.…”

Electrochemical Performance of Carbon-Nanotube-Supported Tubular Diamond

“…The initial diamond crystal structure was composed of 8 carbon atoms in the unit cell which was used for optimization, and it was performed until the force of each atom was less than 0.01 eV/Å and plane wave cut-off energy was 550 eV. For geometry relaxation and density of states calculation, a Monkhorst–Pack grid of 5 × 5 × 5 and 7 × 7 × 7 K -points was used. , …”

Q-Carbon as a Corrosion-Resistant Coating

“…To build an efficient corrosion-resistant material, we have used firmly coupled covalent Q-carbon with the aim of increasing the damage threshold potential and decreasing defect formation. The quenched and random atomic arrangement has been used to encourage the migration of atoms during the liquid phase-mediated growth, which helps in the removal of remaining voids in the Q-carbon structure. – During the formation of Q-carbon, the amorphous carbon is melted by nanosecond laser pulses in a highly undercooled state and subsequently quenched to create a random combination of sp 3 -rich hybridized tetrahedral bonds and sp 2 -hybridized trigonal planner bonds at a dense state with shorter bond length and higher atomic density compared to diamond or DLC. The overall sp 3 proportion in Q-carbon is observed to be more than 80% with the rest of the percentage of hybridized sp 2 and this special structure has been demonstrated to be exceptionally thermally stable with a record hardness of 60% more than that of diamond. , Scanning electron microscopy (SEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) were employed to observe and characterize the unique morphology, Raman active phonon vibrational modes (D and G bands), and chemical and electronic state with sp 2 and sp 3 compositions of Q-carbon, respectively.…”