Studies On Preparation By HFCVD And Wettability Of Amorphous Carbon Films

The wettability of solid surfaces is a very important property. The solid material which has special wettability has attracted much interest because it will play an important role on our daily life as well as in many industrial and agricultural processes, for example, preventing snow, depollution, antioxidation and preventing electric current conduction. As an environmentally benign and economically viable optoelectronic device material, amorphous carbon(a-C)films are paid too much attention for its lots of well properties. Combined with special wettability properties, a-C films may have greater potential applications. In this study, a series of a-C films with different thickness and surface micro-morphology were prepared on Si(100)substrate by Hot Filament Chemical Vapor Deposition(HFCVD), and the growth processes were controlled by adjusting the deposition parameter. The influence of various deposition parameters on the growth rate, the surface morphology and the wettability property of a-C films are studied systematically. The main research work of this study are shown as follow:1. The a-C films with different thickness were prepared by adjusting the deposition parameter. Experiment results indicate that the increase of substrate temperature, pressure and concentration of CH4 can improve deposition rate, and it is mainly influenced by substrate temperature while slightly by pressure and concentration of CH4.2. The a-C films with different surface micro-morphology were prepared by adjusting the deposition parameter. Experiment results indicate that the surface morphology is mainly influenced by substrate temperature while slightly by pressure and concentration of CH4, and the surface of a-C films can vary from smoothness to a complicated microstructure with more and finer nanostructured grooves which is much like the microstructure of nature lotus leaf, so that it is able to absorb and contain more vapors, and the contact angle(CA)increases.3. The wettability property of a-C films with different surface micro-morphology are studied. Experiment results indicate that it can change in large scale from very hydrophilicity (16^o) to very hydrophobicity (143^o) by only adjusting the substrate temperature and is mainly influenced by substrate temperature while slightly by pressure and concentration of CH4, the increase of growth time can improve the contact angle of a-C films and finally steady it.4. The wettability of a-C films are improved remarkably by CF₄ plasma treatments. After a short plasma treatment, the a-C film with a primary contact angle of 83^o became very hydrophobic with a contact angle of 135^o.