A First-principles Study Of Electronic Structures And Functional Devices Based On Graphene With Nanoholes

Abstract:Based on density functional theory (DFT), extended Huckel tight-binding (DFTB) theory and nonequilibrium Green’s function (NEGF) formalism, electronic modification and functional devices-design of graphene material have been studied. This paper focuses on law of bandgap opening/closing of GALs with zigzag-edged hexagonal holes (ZH-GALs) and simulation of transport properties of graphene nanohole DNA sensors.We obtained the general law for estimating bandgap opening/closing of ZH-GALs. Using parameter{[m1,n1],[m2,n2]} to model these lattice structures, we can obtain GALs patterns missed in the previous research work. We found that the antidots could be divided into three categories according to their relative position. Interestingly, it is found only when the number of three categories are unequal, the relatively large band gap can be obtained for ZH-GALs. Also, we show that the bandgap opening in GALs mainly results from the intervalley scattering. These findings should provide a good way to predicte the electronic properties of GALs with desired band gaps, and may be helpful for the design of semiconductor and photoelectronic devices based on GALs.A biosensor device for DNA sequencing built from a graphene nanoribbon (GNR) with a nanopore, was designed and studied by first principles quantum transport simulation. The four DNA nucleobases can be distinguished through investigating the transverse conductance properties with different nucleobases inside the nanopore. Meanwhile, the transverse-current is sensitive to the orientation of nucleobases. The analysis on transmission spectra and frontier orbital energy showed that the transverse-current changes majorly due to the interaction between nucleobases and the device. This interaction causes the reconstruction of molecular orbits of whole device. And this interaction is a long-range effect, make that the nucleobases still be effective impact on the transverse-current when far from nanohole. Therefore, when such devices using for detecting short-chain of nucleobases, the impact of multi-layer nucleobases is needed to consider.