▎ 摘　　要

Recent advances in controlled synthesis of graphene nanodevices urge the understanding of various defects' effect on the electronic transport properties, such as Stone-Wales defects, single vacancy, double vacancies and multiple vacancy chains. In this work, we systematically investigated these defects in single-layer graphene, by using first principle calculations combined with the non-equilibrium Green's function method. The calculated current-voltage curves reveal that these defects can lead to current decrease compared with pristine graphene. Besides, corresponding transmission spectra and device density of states indicate that some defect induced electron states can strongly enhance the transport of electron between electrodes at certain energy levels, while others are only localized around the defect sites. Moreover, the distinct results of graphene with multiple vacancy chains demonstrate that both the number and arrangement of vacancy defects could affect the electronic transport properties of graphene nanodevices. We also verified that these vacancy defects could be easily identified by using a small source-drain voltage and sweeping the gate voltage applied on the graphene field effect transistors. These results are helpful to further understand vacancy defects' impact on the transport properties of graphene nanodevices, and inspiring to tune the electronic behaviors of two-dimensional nano devices through controlled defect engineering modifications.