Electric field-tunable electronic structures of 2D alkaline-earth metal hydroxide–graphene heterostructures
Abstract
Based on first-principles calculations, we study the electronic structures of 2D alkaline-earth metal hydroxide X(OH)2/graphene (X = Ca, Mg) heterostructures. The results show that the characteristics of the band gap size of X(OH)2 and Dirac cone of graphene are preserved well, and p-type Schottky barriers with a small Schottky barrier height (SBH) are formed in the hetero-multilayers. Moreover, double Dirac cones are also found in the X(OH)2/bilayer graphene (X(OH)2/BLG) cases. Interestingly, negative electric fields can easily induce the transition from p-type Schottky to Ohmic contact, while the p-type to n-type Schottky transition can be realized by positive electric fields. In addition, the electric field-modulations of the Schottky barrier are more sensitive in the X(OH)2/BLG systems. These studies may open the possibility of using X(OH)2/graphene as building blocks in the fabrication of Schottky devices.