表面键合对硅（111）量子面电子结构的影响

摘要

将纳米硅薄膜看成理想的一维限制的量子面结构，通过第一性原理计算研究了不同厚度的硅(111)量子面的能带结构及态密度。随着量子面厚度的变化，在 Si-H 键钝化较好的量子面结构上，其带隙宽度变化主要遵循量子限制效应规律。当在表面掺杂时，模拟计算表面含 Si-N 键的硅(111)量子面的结果表明：在一定厚度范围内，带隙宽度主要由量子限制效应决定；超过这个厚度，带隙宽度同时受量子限制效应和表面键合结构的影响。保持量子面厚度不变，表面掺杂浓度越大则带隙变窄效应越明显。同样，模拟计算含 Si-Yb 键的硅(111)量子面的结果也有同样的效应。几乎所有的模拟计算结果都显示：量子面的能带结构均呈现出准直接带隙特征。%We regard the nanocrystalline silicon films as an ideal one-dimensional quantum limiting surface structure, and study the band structure and density of states of the different thickness silicon (111) quantum surface by the first-principles calculation. As the change of the thickness of the quantum surface well passivated by Si-H bond, the band gap mainly follow the quantum confine-ment effect. When the silicon (111) quantum surface contains Si-N bond, the simulated results show that the band gap is mainly determined by the quantum confinement effect in a certain range of thickness, but beyond the thickness, the band gap is determined by both the quantum confinement effect and bond structure. While maintaining a constant thickness, the greater doping concentration of the quantum surface, the more obvious the band gap narrowing effect. Similarly, the simulated result of silicon (111) quantum surface which contain Si-Yb has the same effect. It is worth noting that almost all of the simulated results show that the band structures of the quantum surface show quasi-direct band gap characteristics.