The Preparation Of Diamond Films By DC Arc Plasma Jet CVD

The diamond has excellent mechanics, thermotics, optics, electricity and acoustics performance. The investigation of diamond becomes the focus of the physics and chemistry. As growth rate is concerned, significant high rate occurs in DC arc plasma jet CVD. Performance of diamond thin film depends on its bulk structure and components, the diamond thin film can be characterized by its bulk structure and component. Field emission scanning electronic microscope (SEM) shows its surface morphology;X-ray diffraction (XRD) gains information about its crystal lattices,lattice constant,crystal orientation, crystal defect and stress ; the diamond peak of Raman spectrum is at 1332cm-1.The experiment uses 30kW DC arc plasma jet CVD equipment.By setting up equipment's heat transfer mathematical model,the author simulates plasma torch input power, reaction pressure, deposition platform temperature, reaction cavity wall temperature, the distance between substrate and nozzle, the ratio of solid-phase contact area/total area between substrate and deposition platform respectively affects substrate temperature. The simulation results show that: according to the importance of sequencing followed by plasma torch input power, reaction pressure, deposition platform temperature, reaction cavity wall temperature, the distance between substrate and nozzle. Substrate temperature increases as the power, in a certain temperature range, similar to conics; Substrate temperature with the cavity pressure increases, similar to conics, and the higher the temperature, temperature rate of change of cavity pressure the greater; Compared with the same condition of experimental results, two has similar behavior. The most deviation is about 10%.In the experiment, using the means of measurement, the author discovered that the nucleation density, substrate temperature, concentration of carbon source and plasma torch input power all had a strong influence on the diamond thin film. The experiment shows that growth rate of diamond films with the substrate temperature increases, the diamond films have the best quality between 1000℃and 1100℃; In diamond growth 0.067 of C/Ar ratio is most appropriate; Plasma input power has to retain a constant. By optimizing experimental parameters, free-standing diamond films were prepared.The cracking of diamond film and Substrate temperature control are two mostly troubles in CVD diamond preparation .Because of no any control on the substrate temperature during the whole process, the cracking of diamond film often occurs. The author summarizes the experimental experience, puts forward some ways to solve these problems. The best way is to adopt an additional heat source, so the substrate temperature could be controlled accurately during the experiment and its temperature could be kept for a long time after cutting off the torch power.