REDUCTION IN DEFECT DENSITY BY ANNEALING IN HYDROGENATED TETRAHEDRAL AMORPHOUS-CARBON

Electronic applications of diamond-like carbon have been limited by it s relatively high disorder and defect density. We find that the densit y of paramagnetic defects in hydrogenated tetrahedral amorphous carbon and the Urbach slope of the optical absorption edge can be reduced by annealing at 300 degrees C, with little effect on the optical gap. Th is leads to a reduction in the dark conductivity and an increase in th e photosensitivity. The effect is attributed to the migration of hydro gen through the C-C network, to allow better passivation of dangling b onds and a modification of the more weakly bonded sp(2) clusters with narrower local band gaps. (C) 1998 American Institute of Physics. [S00 03-6951(98)01243-1].