Design The Device Structure And Study Of Electronic Transport Characteristics Of Graphene Nanoribbons

In recent years, with the miniaturization of silicon-based electronic devices and the rapid development of microelectronics technology, molecular devices has become an important research object of the development of electronic devices in the future.And the emergence of graphene brings new opportunity for development of nano-electronic devices. Due to graphene has more excellent performance of electronics than the traditional silicon-based electronic devices. So the graphene nanoribbons electronic devices is likely to replace traditional silicon-based electronic devices. As researchers in many fields focus on graphene, the researchers pay more attention to research of graphene molecular devices in recent years. Many experiments and theorical of graphene studies by cutting and doping, make them form a special geometric structure, so as to show the special properties of electronic devices. Using first principles based ondensity functional theory, the paper systematically calculate electronic structure and transport properties of graphene nanoribbons by cutting design different geometric shapes of nanoribbon devices.By using nonequilibrium Green's functions in combination with the first principles density functional theory, for the double triangle graphene nanoribbons with armchair edge as the research object, take the graphene with armchair edge as electrodes, respectively investigate B(N) doping and B-N co-doping, mainly research the influence of doping for the double triangle armchair graphene nanoribbons device transport properties and the effect of asymmetric doping on rectifying behaviors in double triangle armchair graphene devices. And studied in zigzag graphene as electrodes, respectively B(N) doping and BN co-doping for the effect of asymmetric doping on rectifying behaviors in double triangle zigzag graphene devices.For the armchair graphene as electrodes, the double triangle armchair graphene nanoribbons as the research object, separately B(N) doping and BN doping research.Calculated results show that: after a single class of boron or nitrogen atom substituted with the vertex carbon atom of similar right triangle graphene, enhances the ability of the system conductivity and appears novel rectifying effect. The rectification behavior can be observed because of an asymmetric movement on the molecular-level in B(N)doping in similar right triangle graphene devices under positive and negative biases and the asymmetry in the spatial distribution of the frontier orbitals. Most importantly,when the vertex carbon atom of right and left similar right triangle graphene are simultaneously doped with boron and nitrogen atom, the rectifying effect of the system is significantly enhanced.For the zigzag graphene as electrodes, the double triangle zigzag graphene nanoribbons as the research object, separately B(N) doping and BN doping research.The results showed that the doped enhanced system conductance capability, there has been rectified behavior in different directions, and appears the negative differential resistance effect.Studies have shown that the type of dope atoms and the dope position has a great influence on the direction of rectifying effect.