Electrochemistry of Nanocrystalline 3C Silicon Carbide Films

Abstract

Silicon carbide (SiC) films have been used frequently for high-frequency and powder devices but have seldom been applied as the electrode material. In this paper, we have investigated the electrochemical properties of the nanocrystalline 3C-SiC film in detail. A film with grain sizes of 5 to 20 nm shows a surface roughness of about 30 nm. The resistivity of the film is in the range of 3.5-6.2 kΩ cm. In 0.1 M H(2)SO(4) solution, the film has a double-layer capacitance of 30-35 μF cm(-2) and a potential window of 3.0 V if an absolute current density of 0.1 mA cm(-2) is defined as the threshold. Its electrochemical activity was examined by using redox probes of [Ru(NH(3))(6)](2+/3+) and [Fe(CN)(6)](3-/4-) in aqueous solutions and by using redox probes of quinone and ferrocene in nonaqueous solutions. Diffusion-controlled, quasi-reversible electrode processes were achieved in four cases. The surface chemistry of the nanocrystalline 3C-SiC film was studied by electrochemical grafting with 4-nitrobenzenediazonium salts. The grafting was confirmed by time-of-flight secondary ion mass spectroscopy. All these results confirm that the nanocrystalline 3C-SiC film is promising for use as an electrode material.