孤立分散在SiO_2基质中的半导体InSb纳米颗粒界面效应的MS-XANES研究

MS-XANES Studies on the Interface Effect of Semiconductor InSb Nanoparticles Embedded in a-SiO_2 Matrix

利用MS-XANES计算研究了嵌入在SiO2介质中的InSb纳米颗粒的界面效应,结果显示Sb K-XANES实验谱在白线峰强度增大和白线峰向高能一侧展宽这两个特点的起因是:1．SiO2介质透过界面处强的Sb-O共价键间接地影响和改变了InSb团簇中Sb原子内部的势分布;2．通过InSb纳米颗粒界面处存在着强的Sb-O共价键使得Sb原子的5p电子被耗尽来提高InSb纳米颗粒Sb原子的5p的空穴数．这两方面共同决定了InSb纳米颗粒的Sb K-XANES实验谱在白线峰强度的增大．此外,由于纳米颗粒的界面效应,仅仅把白线峰的强度增大归因于吸收原子电荷转移带来的空穴数增加,并依此通过白线峰的强度计算吸收原子的空穴数是不合理的．

The interface effect of semiconductor InSb nanoparticles （NPs） embedded in a-SiO2 matrix was investigated via multi-scattering XANES simulations. The results show that the white line increase and broadening to higher energies of InSb NPs embedded in a-SiO2 host matrix are mainly due to the interaction of InSb NPs and a-SiO2 matrix. It can be interpreted as both a local single-site effect on tt0（E） due to the effect of a-SiO2 matrix on Sb intra-atomic potential and the increase in 5p-hole population due to 5p-electron depletion in Sb for the InSb NPs embedded in SiO2 matrix. On the other hand, our result reveals evidently that it is not reasonable to estimate the 5p-hole counts only according to the intensity of the white line due to the interface effect of nanoparticles.