Optoelectronic Properties For Graphene Nanoribbons

Graphene(single layer of carbon atoms) has been becoming the hot system because its special structure and the physical property.Graphene has no internal defects with extremely thin and obvious quantum effects,so that it has different characteristics from other two-dimensional physical systems.Graphene has similar functions to those of carbon nanotubes and molecular electronic devices,with outstanding and unique physical, chemical and mechanical properties,and has extensive applications in the design of devices of micro-nano-electronics,optoelectronics and spintronics.Starting from the sp~2 hybrid orbit theory for carbon and energy band theory,this thesis studied the formation of crystal graphene(monlayer of carbon atoms) and its electronic structure.Graphene nanoribbons dispersions have been calculated.Furthermore, the optoeletronic properties for graphene nanoribbons have been calculated and discussed by using the dispersion relations.The thesis is divided into five chapters.The first chapter introduces briefly the research history and the present situation in graphene.Basing on the linear combination of orbit wave functions of carbon atoms,chapter two calculates the concrete expressions of sp~2 hybridization orbit wave functions of graphene covalent bonds,except for the experimental manufacturing and potential applications of graphene.The third chapter presents the electronic structure of graphene basing on the engery theory by using tight-binding approximation.Furthermore,Dirac electronic formula has been derived and the properties of electrons have been dicussed.Chapter four investigates the optoelectronic properties of graphene nanoribbons.According to the characteristics of graphene eletronic structure, we have calculated the dispersion relations of graphene nanoribbons and drawn the dispersion relations figures,the JDOS figures and the real conductance Reσfigures,and studied the optoelectronic properties for the graphene nanoribbons.Chapter two,three and four are mainly our works.In chapter five,a summary of the work and a outlook of this topic are given.