Atomic arrangements, bond energies, and charge distribution on Si(0 0 1) surfaces with the adsorption of a Ge dimer by DFTB calculations
Atomic arrangements, bond energies, and charge distribution on Si(0 0 1) surfaces with the adsorption of a Ge dimer by DFTB calculations
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DOI：
10.1016/j.commatsci.2020.110120
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发表时间：
2021-02
影响因子：
3.3
通讯作者：
Lijun Wu;Baoqian Chi;Longhai Shen;Lin Zhang
中科院分区：
文献类型：
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作者：
Lijun Wu;Baoqian Chi;Longhai Shen;Lin Zhang
SiGe纳米材料的原子排列和电学性质在新型纳米电子器件和光电器件中具有重要意义。利用 DFTB 算法研究了吸附在不同初始高度和倾角的 Si(0 0 1) 表面上的 Ge 二聚体的原子排列、键能和电荷分布。论证了 Ge 二聚体在硅板表面上的八种不同的稳定吸附模式。阐明了八种模式的结构和电特性的变化。不同的初始条件导致Ge二聚体稳定吸附在表面或导致Ge二聚体中的两个单个Ge原子断裂。 Ge二聚体以不同的倾角吸附在表面Si二聚体的顶部位点、桥位位点或中空位点上。 Ge二聚体的键长被拉伸，两个Ge原子失去电荷。 Ge原子距离表面越远，失去的电荷就越多。 Ge二聚体的不同吸附位点影响Si二聚体在表面的性能。顶部吸附位模式对Si二聚体的键长和键能影响较大，而桥吸附位模式对Si二聚体的电子分布影响较大。 Ge 单原子吸附的性质类似于 Ge 二聚体被吸附在桥位上的情况。不同的吸附位点和倾角导致系统的EGap值不同，并且倾角对不同位点的影响也不同。 Ge二聚体和Ge单原子不仅对Si二聚体的性能有相似的影响，而且对EGap也有相似的影响，这表明Si表面的变化是EGap变化的主要贡献者。
The atomic arrangements and electrical properties of SiGe nanomaterials are of significance when used in novel nanoelectronic devices and optoelectronic devices. Atomic arrangements, bond energies, and charge distribution of a Ge dimer adsorbed on Si(0 0 1) surfaces with different initial heights and inclination angles are investigated by using the DFTB algorithm. Eight different stable adsorption modes of the Ge dimer on the Si slab surface are demonstrated. The variations of the structural and electrical properties of the eight modes are elucidated. Different initial conditions caused stable adsorption of Ge dimer on the surface or caused two single Ge atoms from the Ge dimer to fragment. The Ge dimer, with different inclination angles, is adsorbed on the top site, bridge site, or hollow site of the Si dimer on the surface. The bond length of the Ge dimer is stretched, and the two Ge atoms lose charges. The further the Ge atom is from the surface, the more charges it loses. The different adsorption sites of the Ge dimer affect the properties of the Si dimer on the surface. The top adsorption site mode exerts a greater influence on the bond length and bond energy of the Si dimer, while the bridge adsorption site mode exerts a greater influence on the electron distribution of the Si dimer. The properties of the Ge monoatomic adsorption are akin to the case of a Ge dimer being adsorbed on the bridge site. The different adsorption sites and inclination angles cause theEGapvalues of the systems to differ, and the effect of the inclination angle on different sites also differs. The Ge dimer and Ge monoatom not only have similar effects on the properties of the Si dimer, but also exert the similar effects onEGap, suggesting that changes in the Si surface are the main contributors to the change inEGap.