Fig. 1. Top views of two match configurations of monolayer WS₂/graphene heterostructure: (a) Match configuration between 3 × 3 × 1 lateral periodicity of monolayer WS₂ sheet and 4 × 4 × 1 lateral periodicity of graphene; (b) match configuration between 4 × 4 × 1 lateral periodicity of monolayer WS₂ sheet and 5 × 5 × 1 lateral periodicity of graphene. 单层二硫化钨/石墨烯异质结匹配模型的顶视图　(a)单层二硫化钨3 × 3 × 1超胞与石墨烯4 × 4 × 1超胞的匹配模型; (b)单层二硫化钨4 × 4 × 1超胞与石墨烯5 × 5 × 1超胞的匹配模型

Fig. 2. Energy band structures of (a) WS₂ monolayer, (b) graphene and (c) WS₂/graphene heterostructure. The Fermi levels are set to zero and marked by red dashed lines. 单层二硫化钨(a)、石墨烯(b)和二硫化钨/石墨烯异质结(c)的能带结构, 其中费米能级处在0 eV, 用红色的虚线表示

Fig. 3. Calculated total density of states (TDOS) and the corresponding partial density of states (PDOS) of WS₂/graphene heterostructure. 二硫化钨/石墨烯异质结的总态密度以及相应的分态密度

Fig. 4. Three-dimensional charge density difference plots WS₂/graphene heterostructure: (a) Side view; (b) top view. 二硫化钨/石墨烯异质结的三维电子密度差分图　(a)侧视图; (b)顶视图

Fig. 5. Band structures of WS₂/graphene heterostructure under different interface distances. Blue curves denote the contributions from graphene. Panels (a)−(j) correspond to the interface distances of 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.2 Å, respectively. The Fermi level is set to zero and marked by red dotted line. 不同层间距下的二硫化钨/石墨烯异质结的能带图, 其中蓝色曲线代表石墨烯部分的贡献　(a)−(j)分别代表层间距为2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.2 Å, 费米能级处在0 eV, 用红色虚线表示

Fig. 6. Conduction band minimum (CBM), valence band maximum (VBM) and band gap of WS₂ monolayer in the WS₂/graphene heterostructure as a function of interfacial distance. 二硫化钨/石墨烯异质结中二硫化钨部分的导带底、价带顶和带隙在不同层间距的值

Fig. 7. Plots of the plane-averaged electron density difference along the direction perpendicular to the interface of the WS₂/graphene heterostructure under different interface distances of 2.4 Å to 4.2 Å, respectively. 不同层间距下二硫化钨/石墨烯异质结沿着Z方向的平面差分电荷密度图