Investigation Of The Effects Of Parameters On The Diamond Film Quality In MPCVD Apparatus

Diamond has a series of the most extreme physical and chemical properties of allmaterials. Due to the notable properties, such as the highest hardness, the lowestcoefficient of thermal expansion, chemically inert, high wear-resistant, high thermallyconductive, electrically insulate and so on, diamond films find use on a variety ofapplications including, as semiconductor, as an optical component, as heat sink and aswear-resistant coating. The most common process for diamond growth is the chemicalvapor deposition (CVD). Compared with other CVD methods, the microwave plasmachemical vapor deposition (MPCVD) has low deposition temperature, no electrodepollution, highly deposition speed. The MPCVD is the best method of preparation of highquality diamond films.It is well known that the quality of CVD films strongly depends on the nucleation andgrowth conditions. The parameters of nucleation directly affect the performance ofdiamond thin film. Firstly, many parameters were studied in the nucleation, such as carbonconcentration, deposition time, the surface morphology and quality of diamond filmdeposited under different nucleation density were conducted. Our results suggest that highnucleation density results in small grain size, well crystallized and dense films. But thenon-diamond phase will increase with the increase of nucleation density, and the quality ofdiamond films is lower. Low nucleation density results in higher growth rate and lessdense than high nucleation density due to less intense grain growth competition. Theoptimum nucleation parameters were obtained and high quality films could be produced.During the process of diamond growth, each technology parameters, such as thecarbon concentration, substrate temperature, microwave power, deposition pressure anddifferent gases, have a greater impact on the quality of diamond films. The analysis anddiscussion of these parameters on the effects of diamond films were conducted, and theresults of the researches suggested that high carbon concentration results in higher growthrate, small grain size and low quality. Low substrate temperature increased the secondarynucleation and reduced the growth rate. At the same time the diamond grain size was small,the crystalline facets was not clear and the quality of the diamond film was not goodenough. These studies showed that oxygen could promote the growth of diamond film. The growth rate of diamond film increased significantly and the grain size was larger afteradding oxygen in the system. In addition, the full width at half maximum (FWHM) of thediamond Raman peak was7.43cm-1, and the quality of diamond films was excellent. Wehad performed lots of experiment and obtained the optimum parameters for growth of highquality diamond film, which give theoretical direction to preparation high qualitytransparent films.