Diao Yu, Liu Lei, Xia Sihao
J Phys Condens Matter. 2020 Feb 20;32(8):085001. doi: 10.1088/1361-648X/ab55a9. Epub 2019 Nov 8.
The electronic and optical properties of metal (M) atoms adsorbed GaAs nanowires are systemically investigated utilizing first-principles calculations based on density functional theory. Different materials (M = Pt, Ag, Al and Au) and different coverages (1M, 2M, 3M and 4M) are considered to construct surface adsorption models. The calculations show that all metal-adsorbed GaAs nanowire surfaces are stable, and the difficulty of metal atom adsorption on nanowire surfaces follows the rule of Ag > Au > Al > Pt. In addition, the layer distance variation of nanowire surfaces after metal atom adsorption mainly take place near the outmost layer region. In 1M coverage case, the work function is reduced by Pt, Ag, Al adsorption, while increased by Au adsorption. Specially, Pt- and Al-adsorbed GaAs nanowire surfaces are direct band gap semiconductors, but Ag- and Au-adsorbed surfaces are indirect band gap. The adsorption of metals on GaAs nanowire surfaces are via chemisorption. Moreover, metal atom adsorption can enlarger the absorption coefficient of GaAs nanowires, which are gradually enhanced with increasing the coverage of metal atoms.
利用基于密度泛函理论的第一性原理计算方法，系统地研究了吸附在砷化镓纳米线上的金属（M）原子的电子和光学性质。考虑了不同的材料（M = Pt、Ag、Al和Au）以及不同的覆盖度（1M、2M、3M和4M）来构建表面吸附模型。计算结果表明，所有金属吸附的砷化镓纳米线表面都是稳定的，金属原子在纳米线表面吸附的难易程度遵循Ag > Au > Al > Pt的规律。此外，金属原子吸附后纳米线表面的层间距变化主要发生在最外层区域附近。在覆盖度为1M的情况下，Pt、Ag、Al的吸附使功函数降低，而Au的吸附使功函数增加。特别地，Pt和Al吸附的砷化镓纳米线表面是直接带隙半导体，而Ag和Au吸附的表面是间接带隙。金属在砷化镓纳米线表面的吸附是通过化学吸附实现的。此外，金属原子吸附可以增大砷化镓纳米线的吸收系数，并且随着金属原子覆盖度的增加而逐渐增强。
