ENERGY-DEPENDENT STRUCTURE CHANGES IN ION-BEAM DEPOSITED A-C-H

The present study investigates the effect of ion energy in the form of acceleration potential on the structure of ion beam deposited a-C:H f ilms using Raman spectroscopy, FTIR spectroscopy and profilometry. The results indicate that for low acceleration potentials (100-200 V), th e sp(2) fraction of the film becomes more ordered as the acceleration potential increases. However, FTIR indicates that the hydrogen bonding in the film is unaffected. For mid-range acceleration potentials (200 -800 V) the film structure remains stable, then, as the acceleration p otential is increased above 800 V there is a further increase in the o rder of the sp(2) fraction in the films and a change in the hydrogen b onding in the film. These structure changes suggest that two separate energy dependent processes effect the structure of IBD a-C:H; a densif ication/relaxation process at low acceleration potentials and ion dama ge/sputtering processes at higher acceleration potentials.