A PHOTOELECTROCHEMICAL STUDY OF AMORPHOUS HYDROGENATED CARBON-FILMS

The photoelectrochemical behavior of amorphous hydrogenated carbon (a- C:H) thin-film electrodes on tungsten substrates is studied in 0.5 M H 2SO4 solution. The a-C:H films, 50-250-nm thick, are grown by the ion- source deposition and magnetron sputtering. Cathodic and anodic photoc urrent are observed under cathodic and anodic polarization, respective ly, which is characteristic of insulating electrodes or intrinsic semi conductors. The optical band gap width for a-C:H is determined from th e photocurrent spectra; it somewhat varies, depending on the condition s of film growth. A tungsten oxide interlayer forms between an a-C:H f ilm and tungsten substrate under strong anodic polarization, which res ults in the carbon film detachment.