▎ 摘　　要

In this paper, for the first time device characteristics of field-effect tunneling transistors based on vertical graphene-hBN heterostructure (VTGFET) and vertical graphene nanoribbon (GNR)-hBN heterostructure (VTGNRFET) are theoretically investigated and compared. An atomistic simulation based on the nonequilibrium Green's function (NEGF) formalism is employed. The results indicate that due to the presence of an energy gap in GNRs, the ION/IOFF ratio of VTGNRFET can be much larger than that of VTGFET, which renders VTGNRFETs as promising candidates for future electronic applications. Furthermore, it can be inferred from the results that due to smaller density of states and as a result smaller quantum capacitance of GNRs in comparison with that of graphene, better switching and frequency response can be achieved for VTGNRFETs.