Influence of temperature on the hydrogenated amorphous carbon films prepared by plasma-enhanced chemical vapor deposition

Hydrogenated amorphous carbon ( a -C:H) films were deposited in a plasma-enhanced chemical vapor deposition (PECVD) system. The substrate temperature at deposition was found to have significant effects on the film stoichiometry, s p 2 phase, and optical properties. Raman spectroscopy reveals an increase in s p 2 -bonded carbon and a continual structure ordering of the s p 2 phase with increasing substrate temperature at deposition. Thermal desorption spectroscopy analysis revealed that the onset temperature of CH 4 effusion of PECVD a -C:H films increase with increasing substrate temperatures, implicating enhanced structural stability via elevating the substrate temperature at deposition. The extinction coefficient k measured from spectroscopic ellipsometry gradually increases with increasing substrate temperature at deposition, due possibly to the graphitization effect which decreases the optical gap resulting in higher k .