Achieving a higher performance in bilayer graphene FET - strain engineering

In addition to its high mobility, the possibility of opening sizable bandgaps has made bilayer graphene (BLG) a promising candidate for many electronic and optoelectronic applications. Yet, the achievable bandgap (300 meV) is not sufficient to make BLG a candidate for high performance transistors. Vertical strain in conjunction with the vertical field can help to achieve a larger band gap in BLG. In this paper, p_z nearest-neighbor atomistic tight-binding model and Non-equilibrium Green´s Function (NEGF) method are used to study the transport behavior of strained BLG transistors under electric field. A field tunable dynamic band gap (DBG) of up to 300 meV is found to exist in BLG with no strain in agreement with previous reports. By applying strain, one can increase the band gap of BLG beyond 300 meV. Finally, the DBG effect and vertical strain are shown to be able to enhance the ON/OFF ratio of a BLG field effect transistor (FET) to 1000.