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 confinement 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.