Aidin Taghizadeh Abhari - Department of Electrical Engineering, Arak Branch, Islamic Azad University, arak, Iran.
Ashkan Horri - Department of Electrical Engineering, Arak Branch, Islamic Azad University, arak, Iran.

In the recent decades, graphene was taken ‎into research studies, more seriously due to ‎it’s very suitable electronic, optical and ‎mechanical properties at electronic usages. ‎Single layer and multilayer graphenes are used in channel of Field–Effect Transistors (FET). Recently vertical graphene based graphene ‎FET tunneling is taken into ‎consideration.‎ In this model, the source and the drain are composed of a single layer of graphene and hBN is used as the tunneling barrier. However using of graphene in FET for ‎digital circuits is limited, due to lack of ‎energy band gaps. ‎ This paper is focused on simulation of VTGFET, and vertical graphene nano-ribbons (GNR) FET (VTGNRFET). ‎VTGFET characteristics were improved by ‎changing the number of barrier layers. ‎Simulation method of this paper, is the tight ‎binding (TB) and the non-equilibrium ‎Green s function. It is observed that Ion /Ioff ‎enhances by increasing the hBN layer. In addition, ‎the sub-threshold swing decreases. In addition, Ion ‎‎/Ioff increases by increasing the width of ‎Nanoribbon. This paper innovation is using ‎multiple layers of hBN as tunneling barrier. ‎

Graphene; Boron Nitride; Ion/Ioff ‎Ratio; Tunneling Transistors; Green Function