表面氢化的双层氮化硼的结构和电子性质

采用第一性原理方法研究了表面氢化的双层氮化硼的结构和电子性质.考虑了表面氢化的双层BN可能存在的六种主要构型,计算结果表明:AB-BN和AA-BN两种构型最为稳定.进一步分析了氢化后的双层BN最稳定构型的能带和电子性质.AB-BN和AA-BN两种构型的原子薄片均为直接带隙半导体,GGA计算的带隙值分别为1.47 eV和1.32 eV.因为GGA通常严重低估带隙值,采用hybrid泛函计算得到带隙值分别为2.52eV和2.34 eV.在最稳定的AB-BN和AA-BN两种构型中,B-N键呈现共价键,而B-H和N-H则具有明显的离子键的特点.在双轴应变下氢化双层BN原子薄片可以被连续地调节带隙,当晶格常数被压缩约8%时,原子薄片由半导体性转变为金属性.

Structural and electronic properties of hydrogenated bilayer boron nitride

The structural and electronic properties of hydrogenated bilayer boron nitride (BN) were studied by employing the first-principles calculations. Six major polymorphic structures of hydrogenated bilayer BN are considered. Calculated results show that, among them, the AB-BN and AA-BN structures are the most stable ones. The analysis on the energy bands and electronic properties of the two most stable structures are then performed. Structures of AB-BN and AA-BN are both semiconducting with direct band gaps, and the gaps are 1.47 eV and 1.32 eV, respectively, calculated using the GGA method. Since GGA usually severely underestimates the band gap, the hybrid density functional calculations are then conducted, which suggests that the band gaps are 2.52 eV and 2.34 eV for AB-BN and AA-BN structures, respectively. In the most stable structures of AB-BN and AA-BN, B-N bonds show mainly covalent characters, while B-H and N-H bonds exhibit clear ionic characteristics. Moreover, the band gap of hydrogenated bilayer BN atomic sheet can be continuously modulated by biaxial strains. When the lattice constant is compressed by around 8%, the electronic character of the atomic sheet changes from semiconducting into metallic.