Field Emission Performance Of Graphene Array

Graphene is a two dimensional crystal with a single monolayer of carbon atoms packed into a honeycomb lattice with sp2-hybridized. It has attracted great attention and has been studied greatly due to its prominent properties since discovered. For example, it is a semimetal with zero bandgap at room temperature and it has Excellent electrical conductivity, high electron mobility, high thermal conductivity, ultrahigh specific surface area and extreme mechanical properties, which may make it competent for field emission.Field emission is cold cathode electron emission. With high emission current, low power cost and cold emission property, field emission cathode has bright application potential. Graphene has a lot of unique advantage, which makes the graphene as ideal emitters for high current emission and low operate electric field.However, currently graphene as field emission cathode are generally stacked into pieces and distributed randomly, as well as direction of field emission electron and ampere density, which restrict the applications of graphene in field emission.In this thesis, the investigation focuses on the graphene. Based on deep analysis of graphene field emission cathode, the graphene cathode structure and preparation are explored and investigated. Then a new field emission cathode structure and manufacturing process based on vertical graphene array are proposed. The main results are as follows:(1) Field emission properties of upright graphene arrays is simulated by COMSOL and self-designed electronic trajectory calculation software, in order to know the influence of field emission about different cathode distance and different medium around the cathode. The simulation results show that the medium surrounding the cathode have little effect on its field emission properties, but the impact of cathode spacing is significant. Considering the modulation effect of cathode voltage and the limitations of technology, we can determine the optimal value of the cathode distance be 5-10?m.(2) The Ti-Cu-Ti basement structure was designed and manufactured by using magnetron sputtering deposition, photolithography and etching process. The technological parameter in the process of preparation was optimized, in order to get the basement of the convex and concave hole wall for graphene growth.(3) By using acetylene as carbon source, we successful manufactured vertical graphene on the basement structure with using LPCVD. The characteristics and morphology of graphene were analyzed by Raman spectrum and scanning electron microscopy (SEM), proved the feasibility of the process. These results provided the basis for the vertical graphene used as cathode structure in field emission decives.