SiO_2基质中包埋纳米晶Si光电性质的模拟计算

Analog calculation of optoelectronic properties of silicon nanocrystals embedded in SiO_2 matrix

采用第一性原理方法,研究了SiO2基质中包埋纳米晶Si的电子结构及光学性质。结果表明:位于约1.7eV的吸收峰是–0.59eV能级上的电子向由价键畸变产生的1.2eV能级跃迁的结果。纳米Si粒中含不饱和键的Si原子的p轨道对可见光区光的吸收有主要的贡献。同时由于这些缺陷引入的能级使价带、导带在Fermi面发生交叠而表现出导电性。

By using a first-principle method, the electronic structure and optical properties of silicon nanocrystals embedded in SiO2 matrix were investigated. The results show the peak at about 1.7 eV is formed from the transition of the electrons at - 0.59 eV energy level to 1.2 eV energy level generated by valence-bond distortion. The p orbit of Si atoms with unsaturated bond in the silicon nanocrystals mostly contributes to the absorption of visible light. Meanwhile, the energy levels from those defects make the conduction band and valence band overlap at Fermi level, then the crystal shows conductivity.