A computational study on electrical characteristics of a novel band-to-band tunneling graphene nanoribbon FET

In this study, a modified structure was proposed for the band-to-band tunneling field-effect transistor (BTBT-FET) mainly to suppress the ambipolar current with the assumption that the ON state characteristics, especially sub-threshold swing, must not be degraded. The proposed structure uses a dual-material gate as gate contact and a narrow lightly doped region at the drain side of the channel. Electrical characteristics of the proposed device were explored by a mode-space non-equilibrium Green's function (NEGF) formalism in the ballistic limit. A significant reduction in the ambipolar current was seen in simulation results for different values of the drain-source voltages. The results also revealed that the ON current remained the same and the sub-threshold swing got slightly better than that of the main structure. The comparison with the main structure showed that the proposed structure benefited from improved switching characteristics such as delay, switching power-delay product and ION/IOFF ratio. Further comparison indicated that the new structure had improved hot electron effect.