Study on structural fluctuations in amorphous semiconductors by micro-light scattering

非晶半导体缺乏长程有序，而键长和键角等短程有序是守恒的。在两种尺度的顺序之间，在几个10纳米尺度的中程顺序是重要的。例如，非晶材料的光致结晶不是在辐照时立即发生的，而是在辐照的一定潜伏期后发生的。可能在潜行期间形成了一些有序态，而非晶态有较大的波动。本研究的目的是阐明非晶半导体在光致结晶过程中的局部特征，如中程波动和分形结构。在这一年中，已经建立了实验装置，并进行了初步的测量。因此，利用微光学技术观测非晶态起伏存在一定的困难。其中一个原因可能是相关的电子态比波动的空间范围更宽。我们用液体He低温恒温器重新布置了用于拉曼散射测量的光学系统，以研究低温下非晶态的网络振动。

While long-range order is lacked in amorphous semiconductors, short-range order such as bond-length and bond-angles are conserved. Between the two scale of order, the medium-range order in a few 10 nm scale is important. For example, photo-induced crystallization of amorphous materials does not occur immediately at the irradiation, but it proceed after some ratent period under the irradiation. Perhaps some ordering states are developed during the ratent period, and there are large fluctuations in the amorphous states. The aim of this research is to clarify local character of amorhous semiconductors, such as the medium-range fluctuations, and fractal structures in the photo-induced crystallization process. In this year experimental setup has been made, and the measurement has been done preliminarly. As the result, it is difficult to observe amorphous fluctuations by Leyrey-scattering using micro-optics. One reason may be that the relating electronic state is spread wider than spacial range of fluctuations. We have rearranged the optical system for Raman scattering measurement with a liquid He cryostat to study the network vibrations in the amorphous states at low temperatures.