Xe原子吸附对GaAs(110)表面重构的影响

Reconfiguration of GaAs(110)surface with the adsorption of Xe atoms

基于第一性原理的自洽场密度泛函理论(DFT)和广义梯度近似(GGA),利用缀加平面波加局域轨道(APW+lo)近似方法,建立了五层层晶超原胞模型,模拟了GaAs(110)表面结构和单个Xe原子在其表面的吸附.利用牛顿动力学方法,对GaAs(110)表面原子构形的弛豫和Xe原子在GaAs(110)表面的吸附进行了计算.从三种不同的初始构形出发,即Xe原子分别在Ga原子的顶位,As原子的顶位以及桥位,都发现Xe原子位于桥位时体系能量最低.由此,认为Xe原子在GaAs(110)表面的吸附位置在桥位,并且发现吸附Xe原子后GaAs(110)表面有趋向于理想表面的趋势,表面重构现象趋于消失,表面原子间键长有一定的恢复,这与理论预言相符合.

First-principle calculations in the frame of density-functional theory （DFT） in the general gradient approximation （ GGA） are performed by using the augmented plane wave plus local orbital （APW ＋ lo） method for pure GaAs（110） surface and the adsorptions of Xe atoms on it. A supercell consisting of five atomic layers is constructed to simulate the geometical configuration of clean GaAs（110） surface and the adsorption of Xe atoms. The Newton dynamics method is used to relax the atomic positions. Initiating with the Xe atom on top of Ga atom, As atom, and at the bridge site, respectively, it is found that the total energy of the supercell reaches the minimum when the Xe atoms are located at the bridge site. Additionally, it is shown that the adsorption of Xe atoms make the relaxed GaAs（110） surface to return to the ideal crystal geometrical configuration as generally expected.