Masanori Shibahara

Positive and negative direct current bias effects on the microstructures and physical properties of hydrogenated amorphous carbon films prepared by radio frequency plasma chemical vapor deposition

Positive and negative direct current (dc) bias effects were investigated for the synthesis of hydrogenated amorphous carbon films in radio frequency plasma chemical vapor deposition at 0.025 Torr and 200 °C. The applied bias ranged from +250 to −500 V. Both the positive and negative dc bias effects are discussed on the basis of surface and cross‐sectional morphology by scanning electron microscopy, deposition rate, threshold energy for photoelectron emission, contact angle, and adhesive strength of these films. For a negative bias, the surface of the film is very flat. The surface of the film deposited with no bias is somewhat pebbly while that of the film deposited with a positive bias is very rough and shows the presence of pores in the cross section. A negative bias substantially increases the deposition rate, refractive index, wettability, and adhesive strength. With no bias (ground potential), as compared to with a positive bias, there is a little increase in the wettability and adhesive force. The n...

Study of the abrasion property of diamondlike films synthesized on iron

The iron materials coated by the diamondlike carbon (DLC) films are expected to have a wide range of application, however, for these substrate materials some difficulties are still remained compared to that of Si. Hard, flat, and strong adhesive DLC films can be synthesized on Mo coated iron substrates by the ionized deposition technique with the aid of the pretreatment of Ar ion bombardment. The DLC films on iron indicate Vickers hardness of more than 5000 kg/mm2. The abrasion test using B4C powder shows that no corrosion can be observed on the DLC films coated on iron materials. The surface properties of the strongly adhering DLC coated substrates are almost the same as those of the DLC films and these properties are independent of the base materials of the substrates.

Photoelectron Emission Study of Hydrogenated Amorphous Carbon Films Prepared by RF Plasma Chemical Vapor Deposition

The ultraviolet (UV) threshold energy for photoelectron emission of the carbon films synthesized by the RF plasma chemical vapor deposition (CVD) method with additional dc bias negative to the substrate was measured with an atmospheric UV photoelectron analyzer. The additional dc negative bias decreased the UV threshold energy and the amount of CH2 and CH3 groups (hydrogen content) of the carbon films, and increased the Vickers hardness and refractive index. The applied negative bias is considered to promote the formation of a network structure like that of diamond.