Infrared antireflection DLC films by femtosecond pulsed laser deposition

Diamond-like Carbon(DLC) films are deposited by Ti:Sapphire femtosecond pulsed laser(800nm, 120fs-2ps, 3.3W, 1-1000Hz) at room temperature. The substrate is n-type Si(100), and the target is 99.999%-purity graphite. After a great lot of experiments, optimal technical parameters, which are 1000Hz repetition frequency, 120fs pulse-width, 5cm-distance between target and underlay and 10 14 W/cm 2 power-density, were used to deposite 443nm thick DLC film. Raman spectrum measurement shows a broad peak with a center at 1550 cm -1 for all films, similar to those of typical diamond-like carbon films prepared using other methods. And sp 3 -bond content reaches 67% analyzed by XPS. There is no nick on the film when scraped 10 5 times by a RS-5600 friction test machine under the pressure of 9.8N. The infrared transmittance increases along with the oxygen pressure when between 0.03 Pa and 2 Pa. The result shows that oxygen is effective in etching sp 2 -bond content. The extreme infrared transmittance of Si slice deposited DLC film on single surface is higher than 64% at 3-5μm, superior to 53% when being uncoated.