Amorphous conducting films were prepared by means of plasma-assisted chemical vapor deposition, and the direct-current conductivity was monitored at temperatures of between 300 and 4.2K. The films were bombarded with 170MeV I13+ ions to a dose of 1013/cm2, and a decrease in conductivity of between 2 and 3 orders of magnitude was observed. The resultant structural changes and defects were studied by using photoluminescence, persistent photoconductivity, and electron spin resonance techniques. These methods showed that the bombardment-induced defects were of  type rather than  type. These produced a change in the  band by introducing trapping levels into the density of states. In addition, charged C dangling bonds were created.

S.Bhattacharyya, S.V.Subramanyam: Materials Science Forum, 1996, 223-224, 311-6