| The graphene/hexagonal boron nitride Moirésuperlattice is of great theoretical significance and application prospects due to its unique energy band structure,abundant physical and chemical properties.The structural,electronic and optical properties of graphene/boron nitride Moirésuperlattices are investigated using the first-principles calculations based on density functional theory in this dissertation,and including the following aspects:1.The crystal structure,electronic properties and mechanical stability of single（bilayer）graphene,hexagonal boron nitride and the corresponding heterojunctions are investigated.The results show that there are six Dirac cones in the Brillouin zone of graphene/hexagonal boron nitride heterojunction,which are all distributed in the path of the high symmetry point K,and the band gap of the AB2stacked heterojunction is 44.1 me V.The graphene/hexagonal boron nitride heterojunction not only maintains the good properties of graphene,but also overcomes the property of zero band gap of graphene.2.The graphene/hexagonal boron nitride Moirésuperlattice structures are designed and constructed,and the atomic number,Moiréperiod and Moiréwavelength of the superlattice at different twist angles are obtained.The stability of the graphene/hexagonal boron nitride Moirésuperlattice system at specific twist angles is discussed using molecular dynamic method.3.The structural,electronic and optical properties of the graphene/hexagonal boron nitride Moirésuperlattice are investigated at different twist angles.The results show that the band gap at the main Dirac point of graphene increases from 0.7 me V to 7.1 me V at the twist angle changing from 21.79°to 7.34°.In addition,the optical properties of the graphene/hexagonal boron nitride Moirésuperlattice are very sensitive to the twist angle,and the reflectance and energy loss functions vary significantly at different twist angles,indicating that the twist angle can effectively modulate the optical properties. |
