Morphology, structure and properties of diamond-like carbon films prepared by spin coating and RF magnetron sputtering

Nano-diamond particles were deposited onto D263T optical glass substrate by two methods: spin coating and RF magnetron sputtering. In the spin coating experiment, the three initial spin speeds are 1000, 1500 and 2500 rpm, with coating period of 20 s; the three terminal spin speeds are 2500, 3500 and 5500 rpm; the coating period is 35 s. In addition, in the RF magnetron sputtering experiment, three sputtering power values are set to 150, 175 and 200 W, and two argon (Ar) flow values are set to 15 and 25 sccm. The experimental results clearly show that the morphology and roughness of the surfaces of all as-deposited films are improved dramatically. Compared to the uncoated surface, the roughness of the surface of the spin-coated film decreases from 1.553 to 0.450 nm, and its contact angle increases from 48° to 68°. In contrast, the surface roughness of RF magnetron-sputtered film decreases to 0.127 nm, and its contact angle increases to 70° and above. For anti-reflection optical thin film, the transmittance of all as-deposited films is within the range of 91–93% by spin coating, and it can reach 90% by RF magnetron sputtering.