Characterization and Electrochemical Responsiveness of Boron-Doped Nanocrystalline Diamond Thin-Film Electrodes

Abstract

The deposition, characterization, and electrochemical responsiveness of boron-doped nanocrystalline diamond thin-film electrodes is reported. The films consist of clusters of diamond grains, ∼50-100 nm in diameter, and possess an rms surface roughness of 34 nm over a 5 × 5 µm 2 area. The individual and randomly ordered diamond grains are approximately 10-15 nm in diameter, as evidenced by TEM. The ∼4-µm-thick films were deposited by microwave-assisted chemical vapor deposition (CVD) using a CH 4 /H 2 /Ar source gas mixture (1%/5%/95%). Under these conditions, C 2 , rather than CH 3 • , appears to be the dominant nucleation and growth precursor. The nanocrystallinity is a result of a growth and nucleation mechanism discovered by Gruen, which involves the insertion of C 2 carbon dimer into C-H bonds on the growth surface (MRS Bull. 1998, 23, 32). The nanocrystalline morphology results from a high renucleation rate. However, unlike previously reported nanocrystalline diamond thin films that have electrical properties dominated by the high fraction of π-bonded carbon atoms in the grain boundaries, the present films are doped with boron, either using B 2 H 6 or a solid-state boron diffusion source, and the electrical properties appear to be dominated by the charge carriers in the diamond. The films were characterized by scanning-electron microscopy, atomic-force microscopy, transmission-electron microscopy, visible-Raman spectroscopy, X-ray diffraction, boron-nuclear-reaction analysis, and cyclic voltammetry, using Fe(CN) 6 3-/4-, Ru(NH 3 ) 6 3+/2+ , IrCl 6 2-/3-, methyl viologen, Fe 3+/2+ , and 4-tertbutylcatechol. Analytical application of this advanced carbon electrode material for the detection of trace metal ions is discussed.

Nanocrystalline diamond microelectrode arrays fabricated on sapphire technology for high-time resolution of quantal catecholamine secretion from chromaffin cells

“…O 2 , CO 2 , H + , NO) (Patel et al, 2008). Thanks to its chemical stability and wide hydrolysis potential window, the NCD microarray can be also employed for detection of other organic molecules besides catecholamines in both the cathodic and anodic regimes (Show et al, 2003). By differently polarizing the detecting electrodes, the chip has potential application for high-throughput screening of drugs and toxins acting on exocytosis and for measuring neurotransmitter release from in vitro neuronal networks or brain slices.…”

“…Among these technologies, ITO is the most interesting one for producing transparent electrodes and wires (Guillen and Herrero, 2005). It is more transparent than boron-doped NCD and works nicely in the anodic regime (Sun and Gillis, 2006). However, ITO shows a lower chemical stability, especially at acidic pH and cathodic potentials, and a narrower potential window with respect to the ∼3 V of boron-doped NCD electrodes (Sun and Gillis, 2006;Chen et al, 2008;Sen et al, 2009).…”

“…To this purpose we developed a chip prototype made using nanocrystalline diamond thin-film technology on sapphire, patterned with four boron-doped microelectrodes. Diamond is optically transparent, highly biocompatible, chemically inert and can exhibit a quasi-metallic conductivity when properly doped (Show et al, 2003) or functionalised (Ariano et al, 2009). Moreover, the high corrosion resistance of the NCD electrodes ensures a long-term reliability not easily achievable with other elec-0956-5663/$ -see front matter © 2010 Elsevier B.V. All rights reserved.…”

Fabrication and characterization of boron-doped nanocrystalline diamond-coated MEMS probes

“…Moreover, the calculated values of RMS roughness of topography obtained from AFM investigations were 17 and 63 nm for boron-doped and undoped films, respectively. Thus, we could consider both fabricated samples as the typical nanocrystalline diamond (NCD) as defined by previous authors [20,46,47].…”

Boron-doped ultrananocrystalline diamond synthesized with an H-rich/Ar-lean gas system

“…They achieved BDD with a minimum roughness of 34 nm and a resistivity on the order of 0.1 ohm·cm. [25] The present authors began developing boron-doped UNCD in 2009, targeting a super smooth, heavily doped UNCD film as a standard material to enable micro-and nanotechnology for MEMS and other devices, electrochemistry and biosensing applications.…”