New route to the fabrication of nanocrystalline diamond films

Abstract

Nanocrystalline diamond (NCD) thin films offer applications in various fields, but the existing synthetic approaches are cumbersome and destructive. A major breakthrough has been achieved by our group in the direction of a non-destructive, scalable, and economic process of NCD thin-film fabrication. Here, we report a cheap precursor for the growth of nanocrystalline diamond in the form of paraffin wax. We show that NCD thin films can be fabricated on a copper support by using simple, commonplace paraffin wax under reaction conditions of Hot Filament Chemical Vapor Deposition (HFCVD). Surprisingly, even the presence of any catalyst or seeding that has been conventionally used in the state-of-the-art is not required. The structure of the obtained films was analyzed by scanning electron microscopy and transmission electron microscopy. Raman spectroscopy and electron energy-loss spectroscopy recorded at the carbon K-edge region confirm the presence of nanocrystalline diamond. The process is a significant step towards cost-effective and non-cumbersome fabrication of nanocrystalline diamond thin films for commercial production.

Surface Structure-Dependent Low Turn-On Electron Field Emission from Polypyrrole/Tin Oxide Hybrid Cathodes

“…For example, the turn-on field for the GaS nanohorns is 4.2 V/μm, for the aligned CdS nanowires, it is ∼7.8 V/μm, for the multipods, it is ∼7.2 V/μm, for the TiO 2 nanotip array, it is ∼9.4 V/μm, for the nanotube, it is ∼34 V/μm, for the ZnS nanobelts, it is ∼3.8 V/μm, for the ZnO nanowires, it is∼5 V/μm, for the nanonails, it is ∼7.9 V/μm, and for the nanopencils, it is 7.2 V/μm . The turn-on field ∼1.3 V/μm for the PPy/SnO 2 p–n junctions is also less than the electric field observed in different carbon nanostructures such as UNCD (5.6 V/μm), CNTs [(2.3 V/μm), (1.55 V/μm)], UNCD/CNTs (4.9 V/μm), CNT/ZnO films (1.3 and 2.5 V/μm), UNCD-decorated silicon nanowires (3.7 V/μm), GS (4.4 V/μm), GS/CsI (2.5 V/μm), MWCNTs/CsI (3.2 V/m), and various other nanostructures of carbon. − The turn-on field of the prepared p–n junction in PPy is also less than or equal to the MWCNT/PPy nanocomposite (1.4 V/μm) and PPy/tetrabutylammonium-hexafluorophosphate (PPy/TBAPF 6 ) nanowires (3.5 V/μm) . The electron density is strongly dependent upon the work function (Φ) and the field-enhancement factor (β), and the value of β can be obtained from the F–N plots of ln­( J / E 2 ) versus 1/ E as shown in Figure d by considering that Φ is known.…”

“…The electron density is strongly dependent upon the work function (Φ) and the field-enhancement factor (β), and the value of β can be obtained from the F–N plots of ln­( J / E 2 ) versus 1/ E as shown in Figure d by considering that Φ is known. The straight lines between the ln­( J / E 2 ) and 1/ E curves suggest that the electrons are emitted via the cold cathode emission process determined by the barrier tunneling and quantum mechanical processes. − ,− The field-enhancement factors (β) have been evaluated for both samples from the slopes of F–N plots by using the relation , where d is the thickness of spacer. The value of the field-enhancement factor has been calculated from the slope of F–N plots for both the pure and doped PPy samples and are found to be 2142.24 and 5665.45, respectively, which indicates that the PPy/SnO 2 p–n junctions have the higher field-enhancement factor as compared to the PPy and can be attributed to the emission of electrons from the sp 2 -hybridized conjugated structure of PPy assisted with SnO 2 doping and the emission directly from PPy via the higher local electric field.…”

Ultrananocrystalline Diamond-Decorated Silicon Nanowire Field Emitters

“…The SiNWs were first coated with melted paraffin wax that was used as a seeding source. Under the HFCVD conditions, the paraffin wax decomposes, leaving behind abundant sp 3 -C crystallites 34 on the SiNW surface that result in enhanced nucleation of UNCD. Paraffin wax is more efficient in the creation of diamond nuclei than traditional detrimental methods, such as polishing and ultrasonication, which produce substantial surface damage.…”

“…23,31−33 However, these approaches require a sophisticated apparatus and complex processing steps, which are tedious and expensive. On the other hand, building upon the valuable reported information related to diamond and SiNWs and the expertise of our group in the growth of ultrananocrystalline diamond (UNCD) using paraffin wax, 34 we hereby present UNCD/SiNW nanostructures as upgraded electron field emitters.…”

Ferromagnetism appears in nitrogen implanted nanocrystalline diamond films

“…A progress in the microwave plasma enhanced chemical vapor deposition (MW PECVD) [3] was allowed to prepare polycrystalline and nanocrystalline diamond (NCD) films [4][5][6] with an excellent optical quality for possible optoelectronic applications [7][8][9]. The MW PECVD diamond films are purer than the natural diamond ones, because the extrinsically impure elements will be excluded from the composition except some inevitable hydrogencarbon contaminations.…”