The insulating properties of a-C : H on silicon and metal substrates

Amorphous carbon has many important applications. In electronic terms, its use as a dielectric is receiving greater attention. This is particularly im portant for applications in magnetic head devices as a reader gap insulatio n layer. Results are presented for resistivity and breakdown fields for hyd rogenated amorphous carbon on silicon, undoped and doped with nitrogen, usi ng an atomic flux sourer. Current-voltage characteristics were analysed usi ng a numerical algorithm to determine trap densities. The results indicated that such films can meet the breakdown specifications, on silicon, and tha t nitrogen doping improves their characteristics. Thickness trends indicate improvements are likely as gaps are scaled. The density of states determin ation indicated that high breakdown was correlated, in the undoped case, wi th high DOS but this was not so for the doped films. The DOS was found to i ncrease as the thickness decreased. On substrates other than silicon, the f ilms were observed to have increased roughness, poorer adhesion and a more polymer-like quality. These changes were reflected in a reduction in the ob served breakdown field. (C) 2001 Elsevier Science B.V, All rights reserved.