Quantum transport of tunnel field effect transistors based on bilayer-graphene nanoribbon heterostructures

Abstract

Abstract We examine quantum transport properties of a graphene system with several different configurations, which the scatter region and two semi-infinite electrodes are represented by single-layer graphene nanoribbons (SGNR) and bilayer graphene nanoribbons (BGNR) with zigzag edge and armchair edge, geometrically known as a GNR field-effect transistor (GNR-FET). Here, the SGNR/BGNR/SGNR (C2 and C3) and BGNR/SGNR/BGNR (C4) configurations are introduced. The transmission process is the vertical tunneling for the configuration based on C3 heterojunction, while in other configurations should be mostly in-plane, that occurs vertically in the device. The calculations are based on the recursive Green’s function theory within the tight-binding method in the coherent regime. Here, we aim to design high performance ternary by using GNR tunneling field-effect transistors (GNR-TFET). Our numerical results show a metal–semiconductor transition in the SGNR/BGNR heterostructure with sizeable band gap value due to a vertical hopping between the both layers in the BGNR device. Also, the strong configuration-dependent Van Hove singularities appear at different energies in the semi-one-dimension TFET. The findings show that the C1 and C3 configurations deliver the largest and the smallest current up to about 1.4 V among four configurations. Moreover, the gate voltage can control and modulate the C3 configuration more than the others with the ON-current modulated effectively. The value of threshold voltage depends significantly on the vertical hopping parameter for the C3 configuration of the nanoribbon with width of N a = 14 . By controlling the geometrical parameters of the system, the ON–OFF current ratio can be tuned. Our numerical results may serve as a base in designing electronic devices based on graphene structure.