Protrusions on the surface of graphite cathode used in the tetrahedral amorphous carbon film deposition

We report the growth of protrusions on the surface of graphite cathode in a pulsed plasma are-discharge method, which is used for producing tetrahedral amorphous carbon (ta-C) films. The bonding structure of the protrusions were studied using the electron spectroscopy for chemical analyses (ESCA) method and the protrusions were found to consist of pure graphite. The morphology of the protrusions was studied using a scanning electron microscope (SEM). The growth of the protrusions is non-beneficial since ii diminishes the carbon plasma yield in a short time (similar to 1 h:) to a level too low for any practical application. This effect can be eliminated in situ by mechanical abrasion of the surface of the graphite cathode. (C) 1998 Elsevier Science S.A.