Annealing effects on the properties of hydrogenated diamond-like carbon films doped with silicon and nitrogen

We have deposited silicon and nitrogen doped diamond-like carbon (Si–N–DLC) films via plasma-enhanced chemical vapor deposition using H2 as a dilution gas and investigated the annealing effects on their structure, chemical bonding, and mechanical, optical, and electrical properties. The internal stress decreased with increasing annealing temperature, which increased the critical load. For the Si–N–DLC films annealed at 347–490 °C, sp2 C clustering was almost suppressed, and the amount of bound hydrogen increased. The optical bandgap of the Si–N–DLC films changed little even at 490 °C. Si–N–DLC/p-type Si heterojunctions annealed at 270 °C and 347 °C provided higher rectification ratios than heterojunctions annealed at different temperatures. The improvement in the current-voltage characteristics of these heterojunctions was probably due to the reduction of defects in the Si–N–DLC films by the annealing.