Effects of annealing temperature on the mechanical, optical, and electrical properties of hydrogenated, nitrogen-doped diamond-like carbon films

We have deposited nitrogen-doped diamond-like carbon (N-DLC) films by plasma-enhanced chemical vapor deposition using H-2 as a dilution gas and investigated the effects of post-deposition annealing in a vacuum on the film properties. It was found that the optical bandgap slightly increased after annealing at 235 degrees C, whereas it substantially decreased after annealing at 420 and 490 degrees C. At these temperatures, the critical load increased primarily due to a decrease in internal stress. Simultaneously, the amount of bound hydrogen in the films decreased, whereas sp(2) C=C increased and its clustering was accelerated. On the other hand, both friction coefficient and specific wear rate became lowest at 347 degrees C. We found that the N-DLC/p-type silicon heterojunction annealed at 347 degrees C exhibited the highest rectification ratio. These results were discussed based on the structure and chemical bonding states of the annealed films.

Automated summary

The effects of post-deposition annealing on the properties of nitrogen-doped diamond-like carbon films were investigated under hydrogen dilution conditions. The optical bandgap decreased with increasing annealing temperature, while the critical load increased due to a decrease in internal stress. The amount of bound hydrogen decreased, sp(2) C=C increased, and clustering was accelerated. The lowest friction coefficient and specific wear rate were observed at 347 degrees C. The N-DLC/p-type silicon heterojunction annealed at 347 degrees C showed the highest rectification ratio.