| Summary: | 碩士 === 國立交通大學 === 光電工程研究所 === 105 === Recently, the related research paper of graphene has been exponential growth and graphene become the leader of two-dimensional materials field. It based on the excellent electrical properties and suitable, which can be provided in a new optoelectronic components of the flexible transparent electrode. Therefore, the interface between graphene and metal is an important issue. In this thesis, we use Material Studio software and CASTEP module to simulate the condition of interface for graphene-nickel interface (G-Ni (111) interface) with no altered electrical properties and a graphene-gold interface (G-Au (111) interface) with altered electrical properties. The difference of electrical properties between G-Ni (111) interface and G-Au (111) interface can be achieved by analyzes the total energy, work function, electrostatic potential map, band structure and partial density of state. We find that the simulated work function of G-Ni (111) close to the original metal and G-Au (111) is deviates from the original metal. In addition, the appropriate parameters are selected by the convergence analysis, and then perform the geometrical optimization to find the most stable structure.
The results of adsorption energy for G-Ni (111) and G-Au (111) are -0.169 eV, and -0.054 eV, respectively. In the band structure result, the Dirac point of graphene disappears after the formation of G-Ni (111), and also form a new energy band. In G-Au (111) result, the Dirac point does not disappear and is shifted upward by about 0.4 eV from Fermi surface. In partial density of state result, G-Ni (111) is deduced that the s-orbital and p-orbital of the Ni (111) surface are mixed with p-orbital of graphene. On the other hand, the density of states near the Dirac cone in G-Au (111) is affected by gold, which leads to asymmetric shape and low left and right height. Based on the simulation results and the experimental results, it can be determined that the interface of G-Ni (111) is easy to pass the with respect to G-Au (111) and does not need to cross the barrier.
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