Amorphous diamond-like carbon coatings, produced by ion beam assisted physi
cal vapour deposition (IBAD) and plasma enhanced chemical vapour deposition
(PECVD) on Si(100) substrates have been studied by positron beam and other
techniques. Both layers have similar positron annihilation characteristics
and a density of 2.4 +/- 0.3 g cm(-3), and are probably significantly hydr
ogenated In the LEAD sample there is significant damage to the substrate, i
ncluding a deep armorphised region and evidence of defect states at the int
erface to the carbon. (C) 1999 Elsevier Science B.V. All rights reserved.