Study On The Preparation And Properties Of Smooth Diamond-like Carbon Films

In this thesis, the progress on the preparation, structure, surface morphology, and properties of diamond-like carbon (DLC) films were reviewed. DLC films have excellent mechanical properties, high hardness, low coefficient of friction and wear resistance, high Young's modulus and elastic modulus. DLC films also have high rate of resistance, high electric insulating strength, high breakdown voltage and low dielectric constant. In biological engineering, DLC films performed their own unique biocompatibility. At present, the DLC films have been successfully applied to act as the artificial heart, artificial joints and artificial bone areas. In optical aspects, their high rate of photoluminescence and the weak absorption in the infrared bands made them have an excellent light transmission and optical band gap. At present, they have been widely used in mechanical, electronic, optical, thermal, acoustic, medical areas, etc. DLC films will achieve their bright application prospect, more and more scientists pay attention to the researchs and development of DLC films and releated devices, e.g., the USA has treated the DLC films as a national strategy in the 21st century.The diamond-like carbon films were prepared by using the low-pressure plasma enhanced chemical vapor deposition (LPPCVD) with H₂ and Trans-2-butene as source gases, and their structure and properties were futher studied. Their diamond-like structure was demonstrated by using Raman spectrum and XPS spectrum, and the evolution rules of their Raman spectrum and XPS spectrum under different growth parameters were investigated. The content ratio of sp³ and sp² within the DLC films can be modulated by varying the growth parameters, and its highest value achieved 0.67 whileas the content of sp3 reached to 40.16%.The main work parameters, such as flow ratios of source gases, work pressure and RF power etc, will affect the deposition rate and the surface morphology of DLC films. The surface morphology of DLC films were scanned via AFM and SEM. The results showed that the RMS of DLC films can be optimized to be 1 nm with a deposition rate 11.96 nm / min under the condition of pressure 10 Pa, RF powe 10 W, the hydrogen flow 0.5 sccm and Trans-2-butene flow 0.6 sccm.The FTIR spectrum reveals that the structure and composition of the DLC films varied with the T2B/H2 flow ratios, pressure and RF power. The results show that DLC films we prepared mainly contain sp³C-H bonds whileas the sp²C-H bonds were not found from their FTIR spectrum, the films possess more C=C bonds when they were prepared under lower T2B/H2 flow ratio, or higher RF power, or lower pressure.The UV-VIS spectrum shows that the transmission ratio of the DLC films reaches 98% in the visible light range, the films have strong absorption in the ultraviolet bands, and their optical band gaps vary in the range of 2.328～2.82eV. Its optical band gap has a close relationship with the structure, particularly the content of the sp³ hybrid bonds and the C = C bonds.The thermogravimetric analysis shows that the mass will loss more when excessive or too little hydrogen in the films, the dense DLC films can be deposited with an appropriate proportion of hydrogen. The results also verify the content of hydrogen in the process of preparation films has a great influence on the quality of the DLC films. It is also observed that films deposited under higher pressure have higher cracking temperature. The thermal stability of DLC films can be improved by adjusting the deposition parameters and annealing treatment. It is believed that the diamond-like carbon films will have a better prospect in inertial confinement fusion (ICF) experiment.