▎ 摘　　要

Zigzag-edged graphene nanoribbon (ZGNR) has great potential in designing quantum waveguide devices to conduct electric currents metallically. Using non-equilibrium Green's function (NEGF) method, we theoretically study geometry dependent transport properties and current-voltage (I-V) characteristics of T-stub ZGNR quantum waveguides sized in tens of nanometers. Instead of the perfect transmission in straight ZGNR, anti-resonance effects appear in transmission spectrum due to strong electronic reflection depending on the size of central region in T-stub ZGNR. In addition, the I-V characteristics of T-stub ZGNR quantum waveguides are mainly influenced by the transverse width of the central region. Meanwhile, the current flowing over the T-stub ZGNR quantum waveguides gradually converges as the longitudinal length of the central region increases. We also find that a single edge-defect at certain positions of the central region may slightly suppress the transmission and reduce the current. Our findings provide a viable design option for adjusting current response in graphene-based quantum devices.