锯齿形石墨烯带(7-ZGNR)输运性质的研究

Research on Transport Properties of Zigzag-Graphene Nanoribbon(7-ZGNR)

采用基于密度泛函方法的非平衡格林函数，对无限长锯齿形石墨烯带（7-ZGNR）的态密度和输运性质进行了理论计算和模拟。结果表明，此石墨烯带的电子输运系数和其态密度有关，波峰与波谷分别相对应。此外，输运曲线近似在费密能级两边对称。由于宽度只有10nm左右，石墨烯带受量子效应的影响，对不同本征能量的电子的输运系数呈整数变化，相应的电导呈现阶跃式变化，其值均为量子电导G0的整数倍。另外，给石墨烯带加以0～1．5V的偏压，计算I-V曲线。结果发现，此石墨烯带在0～1．5V内的I-V曲线接近于线性，考虑到其带隙值较小，因此可认为7-ZGNR是金属型的锯齿形石墨烯带。采用类似的方法，可以判定其他石墨烯带的输运性质。

Non-equilibrium Green＇s functions method based on DFT was adopted to calculate the density of states and transmission properties of a infinite zigzag-graphene nanoribbon （7-ZGNR）. The results show that the electron transport coefficient of the graphene nanoribbon is related to the density of states, and corresponds with the peaks and troughs respectively. In addition, the transmission curve presents approximately centro-symmetric at the both sides of feimi level. Due to the only 10 nm width of the graphene nanoribbon and the affect of quantum effects, the graphene nanoribbon shows integral changes to electron transport coefficient of different eigen energies and step-type changes to corresponding conductance, the conductance value is the integral multiple of the quantum conductance Go. Furthermore, I-V curve was calculated by adding 0 - 1.5 V bias to the graphene nanoribbon. The result shows that the graphene nanoribbon is aooroximately linear in 0- 1.5 V. Considering that the energy gap is smaller, the 7-ZGNR can be considered as a metal zigzag-graphene nanoribbon. The transmission properties of other graphene nanorib- bons can be found out using this method.