| The outstanding features of diamond are its unique mechanical, electrical, thermal, acoustical and optical properties. These specific characteristics made diamond an excellent material for many applications and made people attach importance to it.Direct current hot cathode plasma glow discharge chemical vapor deposition (DC-HCPCVD) is a new method to deposit high quality diamond films with high growth rate. Comparing with the conventional cold glow discharge, the hot cathode glow discharge is a new type of gas discharge. The discharge characteristics have been studied and some regularities have been revealed. But for the discharge current, which can be easily observed and controlled during the deposition process, some special properties about it are still unknown to us. In this thesis, the relations between discharge current and other parameters, such as discharge voltage, cathode temperature and glow discharge state, were researched and the experiment data of Scanning Electronic Microcopy(SEM),Raman Spectrum and X-Ray Diffraction(XRD) of diamond films ere studied. Then the function of discharge current in the deposition process and its effect on the diamond films are summarized. The function of discharge current in the deposition processDuring the discharge process, the discharge region can be regarded as a resistance. Under the conditions that the glow discharge is stabilized and other deposition parameters are immobilized, different discharge current leads to different discharge voltage. And the relation between them can be found. When the discharge current varies from 6.0A to 10.0A, the discharge voltage increases with the increasing of the current. But the augment trend of the voltage is weakened gradually as the current increases. It can be concluded that the saturation of the voltage will appears when the current is high enough. The specialty of the method of DC hot cathode plasma glow discharge CVD can be described by the cathode temperature, which can be analyzed by observing the variation trend of the surface color of the cathode and measured by the optical thermometer. The variation trend of the cathode temperature with the increasing of the discharge current at the different methane flow rate at 2sccm and 3sccm is very obvious. Conclusion is made in this thesis that at the different methane flow rate, the cathode temperature increases as the discharge current increases.Every deposition parameters has their own influence upon the glow discharge state. According to the photos of the glow discharge state under the different discharge current, the variation rules of the glow discharge state are concluded as follows: when the discharge becomes stable, the shape and the color of the sphere of plasma vary regularly with the increasing of the discharge current. The axial length of positive column plasma region is increased. The part near the Faraday dull area shows the trend of expanding and leads to the augment of the volume of the plasma sphere. The color of the plasma sphere changes from purple to light cyan then to the visible cyan, compressing the purple part to the anode fall region. 2．The influence of discharge current upon the diamond filmsMany deposition factors have influences on the diamond films. The discharge current has obvious effect on not only the other deposition factors but also the quality of diamond films. So it is significative to study the variation regularities of the quality of diamond films under the different discharge current.Increasing the growth rate of diamond films is one of the most important targets during the deposition process by the method of DC hot cathode plasma glow discharge CVD. At the methane flow rate of 3sccm, as the discharge current increases, the growth rate first increases to a maximum and drops afterwards. When the methane flow rate decrease to 2sccm, the growth rate of diamond films keep decreasing through the whole experiment process (the current varies from 6.0A to 10.0A). The increase of the discharge means the enhancement...
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