The Preparation And Photo-electron Emission Character Of SiC Thin Film

Pulsed-controlled grid traveling wave tubes become the key components in the national defenses, modern weapon, and navigation in the space and GPS system. It is also especial importance to prolong the working life of tubs for its short function period. In this paper, we discuss the preparation and photo-electron emission character of SiC thin film by the measurement of the Raman Spectrum (Raman), Scanning electron microscopy (SEM), X-ray diffraction (XRD) etc. Furthermore we research the structure and phase change of molybdenum grid coated with silicon and carbon composite thin films under high temperature. And the effect that si-c composite thin film has on the suppressing grid emission in pulsed-controlled grid traveling wave tubes has been studied.Si-C composite thin films were deposited on molybdenum grids by radio-frequency magnetron sputtering technology from the silicon and carbon composite target. The as-deposited films were annealed in the temperature range from 973K to 1273K. In order to simulate the working conditions of the grids contaminated by BaO from the activation of hot cathode in Pulse-controlled grid traveling-wave tubes (TWTs). BaO layers were deposited on the surface of the as-deposited thin films by the chemical method. The compositional and phase change of the samples were investigated after annealing from 973K to 1273K.The structure and phase change of BaO/Si-C/Mo systems under high temperature are discussed according to the experimental results and the calculation of the reaction free energy. The results indicate that graphite and silicon on the surface of Mo grids can prevent BaO from accumulating on the grid surfaces. SiC (about 4.4eV) and SiO2 (about 3.1eV) with high work function are the last products on the surface of Mo grids. Therefore, the silicon and carbon composite thin films deposited on the Mo grid surface can effectively suppress the grid electron emission.