The structure and electrochemical behavior of nitrogen-containing nanocrystalline diamond films deposited from CH4/N2/Ar mixtures.
Electrically conductive nanocrystalline diamond films (approximately 750 to 1000 nm thick) were deposited on conducting Si and W substrates from CH{sub 4}/N{sub 2}/Ar gas mixtures using plasma-enhanced chemical vapor deposition. Such films are continuous over the surface and nanometer smooth. The grain size is 3 to 10 nm, and the grain boundaries are 0.2 to 0.5 nm wide (two carbon atoms). Nitrogen appears to substitutionally insert into the grain boundaries and the film concentration ({approx}10{sup 20} atom/cm{sup 3}) scales with the N{sub 2} added to the source gas mixture up to about the 5% level. The nitrogen-incorporated films are void of pinholes and cracks, and electrically conducting due in part to the high concentration of nitrogen impurities and or the nitrogen-related defects (sp{sup 2} bonding). The films possess semimetallic electronic properties over a potential range from at least -1.5 to 1.0 V vs. SCE. The electrodes, like boron-doped microcrystalline diamond, exhibit a wide working potential window, a low background current, and high degree of electrochemical activity for redox systems such as Fe(CN)6{sup -3/-4}, Ru(NH{sub 3}6{sup +3/+2}), IrCl6{sup -2/-3}, and methyl viologen (MV{sup +2/+}). More sluggish electrode kinetics are observed for 4-methylcatechol, presumably due to weak adsorption on the surface. Apparent heterogeneous electron transfer rate constants of 10{sup -2} to 10{sup -1} cm/s are observed for Fe(CN)6{sup -3/-4}, Ru(NH{sub 3})6{sup +3/+2}, IrCl6{sup -2/-3}, and MV {sup +2/+} at films without any pretreatment.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC); EE
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 943005
- Report Number(s):
- ANL/CHM/JA-36643; JESOAN; TRN: US201002%%502
- Journal Information:
- J. Electrochem. Soc., Vol. 148, Issue 1 ; Jan. 2001; ISSN 0013-4651
- Country of Publication:
- United States
- Language:
- ENGLISH
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