Adsorption mechanism of Pt, Ag, Al, Au on GaAs nanowire surfaces from first-principles
Adsorption mechanism of Pt, Ag, Al, Au on GaAs nanowire surfaces from first-principles
复制标题
DOI：
10.1088/1361-648x/ab55a9
复制
发表时间：
2019-11
期刊：
影响因子：
--
通讯作者：
Yu Diao;Lei Liu;Sihao Xia
中科院分区：
文献类型：
--
作者：
Yu Diao;Lei Liu;Sihao Xia
利用基于密度泛函理论的第一性原理计算方法，系统研究了金属（M）原子吸附GaAs纳米线的电子和光学性质。考虑不同材料（M = Pt、Ag、Al和Au）和不同覆盖度（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GaAs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。另外，金属原子吸附后纳米线表面的层距变化主要发生在最外层区域。在1 M覆盖度下，Pt、Ag、Al吸附使功函数减小，而Au吸附使功函数增大。特别地，吸附Pt和Al的GaAs纳米线表面是直接带隙半导体，而吸附Ag和Au的表面是间接带隙半导体。金属在GaAs纳米线表面的吸附是通过化学吸附实现的。金属原子的吸附使GaAs纳米线的吸收系数增大，且随着金属原子覆盖度的增加，吸收系数逐渐增大。
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.