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采用蒸发法在不同条件下制备了不同大小的嵌埋团簇 Ge∶ Ca F2 膜 ,团簇尺寸介于 2 .1nm～ 7.8nm。电子衍射分析表明 ,Ge∶ Ca F2 团簇为微晶结构 ,晶格常数相对于体材料发生了 4.8%左右的膨胀 ;其光吸收性质表现出了明显的量子受限效应 ,随着团簇尺寸的减小 ,光吸收边蓝移 ,带隙变宽 ;从吸收强度可以看出 ,处于团簇状态 ,Ge出现了从间接带隙到直接带隙的转变。
Different sizes of embedded clusters Ge:Ca F2 were prepared by evaporation under different conditions. The sizes of the clusters ranged from 2.1 nm to 7.8 nm. Electron diffraction analysis shows that Ge: Ca F2 cluster is a microcrystalline structure with a lattice constant of about 4.8% with respect to the bulk material. The light absorption properties of the Ge: Ca F2 cluster exhibit significant quantum confinement effects. With the cluster size , Blue shift of light absorption edge and wide band gap. It can be seen from the absorption intensity that in the cluster state, Ge changed from indirect band gap to direct band gap.