INVESTIGATION OF RIGIDITY PERCOLATION, MEDIUM-RANGE STRUCTURES AND FRACTON IN MULTI-COMPOUND GLASSY SEMICONDUCTORS

我们全面研究了硫系玻璃中纳米结构单元在玻璃转变温度附近的驰豫行为、晶化结构的变化、带尾附近的电子结构以及光激发载流子的驰豫过程中的作用。首先，我们证明了Se_n(n&gt；2)链段的变化本质上决定了网络的驰豫行为。我们还发现，共振拉曼光谱的成分依赖关系可以用Se_n链和Cst链的长度变化来解释。其次，我们发现Ge-Ge类Ethan单元、Se-Se键和类似于β-GeSe_2的片断的本征不均匀性可以导致GeSe_2玻璃宏观结构的显著变化。最后，我们证明了形成Se-Se键的三配位Se原子在GeSe_2玻璃的光诱导结构变化和光激发载流子动力学中起着关键作用。

We have presented a comprehensive study of the roles of nanoscopic structural units in chalcogenide glasses in relaxation behaviors around glass transition temperature, structural changes toward crystallization, electronic structures around band-tails, and relaxation processes of photoexcited carriers.First, we have shown that the variation of Se_n (n>2) chain segments essentially determines relaxational behaviors of networks. We have also shown that the compositional dependence of resonant Raman spectra is explained by the variation in lengths of the Se_n chain and the CST chain. Second, we have found that intrinsic inhomogeneity in Ge-Ge ethan-like units, Se-Se bonds, and fragments similar to β-GeSe_2 can cause significantly different macroscopic structural changes in GeSe_2 glass. Finally, we have demonstrated that threefold-coordinated Se atoms forming Se-Se bonds play a key role in the photoinduced structural change and the dynamics of photoexcited carriers in GeSe_2 glass.