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

非晶半导体中缺乏长程有序，而键长和键角等短程有序则是守恒的。在这两个量级之间，几个10 nm量级的中程有序是重要的。例如，非晶材料的光诱导结晶不会在照射时立即发生，而是在照射下的一段时间后进行。在反应期间可能形成了一些有序态，并且在非晶态中存在较大的涨落。本研究的目的是阐明非晶半导体在光诱导晶化过程中的局部特征，如中程涨落和分形结构。本年度初步建立了实验装置，并进行了测量。因此，很难观察到非晶波动的瑞利散射使用显微光学。一个原因可能是相关的电子态比波动的空间范围更宽。我们重新安排了用液氦低温恒温器测量拉曼散射的光学系统，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.