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

• Published in: Thin solid films Vol. 745; p. 139100
• Main Authors: Osanai, Hiroya, Nakamura, Kazuki, Sasaki, Yuya, Koriyama, Haruto, Kobayashi, Yasuyuki, Enta, Yoshiharu, Suzuki, Yushi, Suemitsu, Maki, Nakazawa, Hideki
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.03.2022
• Subjects: Chemical vapor deposition; Diamond-like carbon; Hydrogen; Nitrogen; Post-deposition annealing; Diamond-like carbon; Post-deposition annealing; Nitrogen; Hydrogen; Chemical vapor deposition
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2022.139100

•Nitrogen-doped diamond-like carbon (N-DLC) films have been annealed in a vacuum.•The optical bandgap increased at an annealing temperature of 235 °C and then reduced.•The friction coefficient and wear rate became lowest after annealing at 347 °C.•N-DLC/p-type Si junction annealed at 347 °C showed the highest rectification ratio. We have deposited nitrogen-doped diamond-like carbon (N-DLC) films by plasma-enhanced chemical vapor deposition using H2 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 °C, whereas it substantially decreased after annealing at 420 and 490 °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 sp2 C=C increased and its clustering was accelerated. On the other hand, both friction coefficient and specific wear rate became lowest at 347 °C. We found that the N-DLC/p-type silicon heterojunction annealed at 347 °C exhibited the highest rectification ratio. These results were discussed based on the structure and chemical bonding states of the annealed films.