Flat Diamond Film Research Articles

Bio-inspired transparent and antibiofouling diamond films via layer-by-layer self-assembly seeding

Bio-inspired diamond nanostructures featuring high transparency and anti-bacterial adhesion were constructed via layer-by-layer (LbL) self-assembly seeding and chemical vapor deposition growth. The topography of the diamond nanofilms was determined by initial nanodiamond seeds distribution, which was adjusted by nanodiamond colloidal stability. With increasing number of LbL bilayers, the bulge size and roughness of the deposited films increased. With increasing number of bilayers from 1 to 5, UV–Vis transmittance slightly decreased from max. 90 %–83 %, while the contact angle increased from 90° to 130°. All the nanostructured diamond films possess very high IR transmittance between 85% and 90%, which is close to the bare quartz (95%). Compared with conventional flat diamond films, nanostructured diamond films repelled most of the bacteria, suggesting excellent anti-biofouling property. With increasing seeding bilayer number, more bacteria were repelled. The highest bacterial reduction was achieved to 99% by diamond film seeded with 5 bilayers. The bio-mimicking nanostructured diamond film represent a potent solution for achieving highly transparent, anti-biofouling and highly durable optical coatings for biomedical and marine optical instrument.

Diamond network: template-free fabrication and properties.

A porous diamond network with three-dimensionally interconnected pores is of technical importance but difficult to be produced. In this contribution, we demonstrate a simple, controllable, and "template-free" approach to fabricate diamond networks. It combines the deposition of diamond/β-SiC nanocomposite film with a wet-chemical selective etching of the β-SiC phase. The porosity of these networks was tuned from 15 to 68%, determined by the ratio of the β-SiC phase in the composite films. The electrochemical working potential and the reactivity of redox probes on the diamond networks are similar to those of a flat nanocrystalline diamond film, while their surface areas are hundreds of times larger than that of a flat diamond film (e.g., 490-fold enhancement for a 3 μm thick diamond network). The marriage of the unprecedented physical/chemical features of diamond with inherent advantages of the porous structure makes the diamond network a potential candidate for various applications such as water treatment, energy conversion (batteries or fuel cells), and storage (capacitors), as well as electrochemical and biochemical sensing.

Synthesis and field electron emission characteristics of diamond multilayer films grown by graphite etching

Diamond multilayer film with nanocrystalline diamond film coated on a layer of diamond nanocone film, was synthesized on silicon substrates by using in situ graphite etching in a hot filament chemical vapour deposition reactor. Many small and sharp protrusions on the surface of the multilayer film were observed using scanning electron microscope and atomic force microscope. The multilayer film exhibits lower turn-on field and larger emission current than flat diamond films and diamond nanocone films. Field electron emission measurements at different residual gas pressures indicate that emission current of the multilayer film shows no obvious degradation and the Fowler–Nordheim (F–N) plots parallel to each other when the residual gas pressure is increased from 10−7 to 10−5 Torr. At a higher pressure of 10−3 Torr, obvious degradation of emission current was observed. The slope of the F–N plot becomes larger, indicating that the work function is increased. The possible reason is that the surface of the multilayer film is fully covered by residual gas molecules.

Fabrication and characterization of phosphorus-implanted mold-type diamond field-emitter arrays

Phosphorus implantation was applied to the fabrication of mold-type diamond field-emitter arrays (FEAs) for the first time. The fabricated diamond FEAs were structurally and electrically investigated and the results were compared with those of flat diamond films under the same implantation conditions. When the diamond films were implanted after they were grown by microwave-plasma chemical vapor deposition (MPCVD), improved field emission characteristics were obtained. From previous work and these electrical results, it is possible to infer that implanted phosphorus ions collect around the Mo–diamond interface and give rise to enhancement of the field emission properties from Mo to vacuum through diamond.

Field emission properties of the polycrystalline diamond-coated silicon emitters

This work examines the electron emission characteristics of a polycrystalline diamond-coated silicon field emitter fabricated by hot filament chemical vapor deposition. The electron emission behavior of a polycrystalline diamond-coated Si field emission array (D/Si-FEA) was compared with that of an uncoated Si field emission array (Si-FEA) and flat-diamond film coated on Si substrate (flat-D/Si). From Raman spectrum and x-ray diffraction pattern analyses, it was revealed that the overcoated diamond film involved structural defects, graphite inclusion, grain boundaries, and a negative electron affinity surface. The direct current current–voltage (I–V) characteristics exhibited linear ohmic emission behavior at low anode voltages and Fowler–Nordheim emission behavior at high anode voltages. The threshold voltages for the D/Si-FEA, Si-FEA, and flat-D/Si were about 250, 666, and 800 V, respectively. The maximum emission current for the D/Si-FEA, 0.23 mA, was obtained for a 500 V anode bias. The low onset voltage of the D/Si-FEA was attributed to the cone-shaped emitter and the excellent properties of the overcoated diamond film.

Emission characteristic of diamond-tip field emitter arrays fabricated by transfer mold technique

Wedge-shaped diamond-tip field emitter arrays were fabricated and characterized. The tip radius of the diamond emitter fabricated by using a silicon mold was about 300 Å. The maximum current density of 800 μA/cm2 and the threshold voltage of 600 V were obtained from the diamond-tip field emitter array, which was a better electrical characteristic than that of a flat diamond film. The effects of vacuum pressure upon emission characteristics were investigated. The emission characteristic of the diamond-tip field emitter array was not varied over a wide range of vacuum pressure relatively to the flat diamond film.

Study on the Diamond Field Emitter Fabricated by Transfer Mold Technique

ABSTRACTStrip-shaped diamond-tip field emitter array was fabricated by using the transfer mold technique. The sharp turn-on characteristic was observed from the current-voltage measurement of the fabricated diamond-tip field emitter array. The turn-on characteristic of the diamond-tip field emitter array was compared with that of a flat diamond film. High emission current density was obtained from the diamond-tip field emitter array. The threshold voltage of the diamond-tip field emitter array was lower than that of a flat diamond film.