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采用基于第一性原理的密度泛函理论平面波超软赝势方法计算了(2×2)GaN(0001)清洁表面的能带结构、态密度、表面能、功函数和光学性质.发现弛豫后GaN(0001)表面的能带结构发生较大变化,表面呈现金属导电特性,导带底附近存在明显的表面态,在偶极矩的作用下表面电荷发生转移,Ga端面为正极性表面;计算获得了GaN(0001)表面的表面能和功函数分别为2.1 J·m~(-2)和4.2 eV;比较分析了GaN(0001)表面和体相GaN的光学性质,发现两者存在较大差异.
The energy band structure, density of states, surface energy, work function and optical properties of the (2 × 2) GaN (0001) cleansing surface were calculated using the first-principles density functional theory plane wave super soft pseudopotential method. The band structure of the GaN (0001) surface changes greatly. The surface presents the metal conductive property. There is a clear surface state near the bottom of the conduction band. The surface charge shifts under the action of dipole moment, and the Ga end surface is the positive polarity surface. The surface energy and work function of the GaN (0001) surface were calculated to be 2.1 J · m -2 and 4.2 eV, respectively. The optical properties of the GaN (0001) surface and bulk GaN were compared and analyzed. Big difference.