Preparation And Properties Of A-C/a-C:H Films Deposited At The Various Incident Angle Of Deposition Particles

The a-C/a-C:H films were deposited on n-type Si(111) substrates by medium frequency magnetron sputtering C target in an Ar/Ar+CH4 glow discharge. The effect of the incident angle of deposition particles and the period of grazing incident(substrate rotation speed) on the surface morphology, microstructures, mechanical and tribological properties of the films were investigated. The major conclusions of this thesis were drawn as follows:1. The influences of the incident angle of deposition particles on the surface morphology, microstructure and properties of the a-C films were inverstigated. The results showed that with the increase of incident angle, the deposition rate decreased in nearly cosine law and the RMS surface roughness through mild and sharp increase stage. XPS and Raman analysis results showed that the sp3/sp2 ratio of the a-C films decreased as the incident angle increased from 0° to 75°, the hardness of the films exhibited a tendency of reduction. Meanwhile, the internal stress changed from compressive stress to tensile stress for domain value of 30° to 45°. The films exhibited a higher friction coefficient and inferior wear risistance with the increasing of incident angle.2. The influences of the incident angle of deposition particles on the surface morphology, microstructures and properties of the a-C:H films were investigated. The results showed that the deposition rate of the films first increased and then decreased as incident angle increased. It is found that the film with the highest deposition rate of 10.24 nm/min was obtained at the incident angle of 15°. The surface roughness of the films increased with the incident angle increased, which is attributed to accelerating the shadowing effect by the increasing of incident angle. Combined with the analysis of Raman and XPS, the results showed that the sp3C-C(H)/sp2C=C ratio of the a-C:H films in the range of 0.86-1.22, which is non-monotonously decreased with the increasing of incident angle of deposition particles. Similarly, the internal stress of a-C:H films changed from compressive stress to tensile stress with the increasing of incident angle. It is found that the film with the highest hardness of 14.22 Gpa and much lower internal stress of-0.037 Gpa was obtained at the incident angle of 30°. Therefore, the DLC films with super-lower internal stress and excellent hardness can be deposited by well adjusted the incident angle of deposition particles.3. The influences of the substrate rotation speed on the surface morphology, microstructures and properties of the a-C/a-C:H films were investigated. The results showed that the growth modes of the a-C/a-C:H films are changed from continuous growth to atomic layer and/or molecular layer growth while substrate rotating. For the a-C films, the deposition rates of the films deposited on rotary substrate monotonously decreased in the range of 0.5-0.32 nm/min as substrate rotation speed increased, which is about a third of the deposition rate of the film deposited on stationary substrate. It is found that the film with most smooth surface of surface roughness is 0.38 nm was deposited at the rotation speed of 3 r/min, after this, the surface roughness of the films increased with the increasing of substrate rotation speed. The sp3/sp2 ratio and hardness of the films decreased and exhibited a poor wear resistance with the increasing of substrate rotation speed. For the a-C:H films, the deposition rates of the films deposited at rotary substrate is about 1/2 times compared with the film deposited on stationary condition; the surface roughness of the films were changed in the range of 0.21-0.58 nm at different substrate rotation speed, and contrary to the a-C films, the max value of surface roughness was obtained at rotation speed of 3 r/min. The a-C:H films exhibited a relatively higher hardness and modulus which were deposited under substrate rotation conditions.