Studies of carbon ion self-implantation into hydrogenated amorphous carbon films

The properties of polymer-like amorphous hydrogenated carbon thin films with low defect density have been studied. These films were implanted with carbon ions with a dose range of 10¹² - 10¹⁶ cm^-2. The purpose of the study is to investigate the effects of ion beam damage on this type of film. Optical absorption measurements observe a narrowing of the optical band gap, suggesting the introduction of a large number of defect states subsequent to the implantation resulting in the broadening of the band tails, only after a threshold ion dose of 10¹⁵ cm^-2. Nuclear reaction analysis suggests also a reduction in the hydrogen content of the film which coincides with film thinning.