アンジュレータ光源を使用した軟 X 線励起による a-Si 膜表面の Si 原子移動

We investigated the characteristics of a-Si film with thicknesses of 1 and 50 nm those were irradiated by soft X-ray from the undulator source. The cohesion of Si atoms were observed after X-ray irradiation for 1 nm-thick a-Si, but it was not observed for 50 nm-thick a-Si. The average roughness Ra of 1 nm-thick-Si film were changed from 0.63 to 1.7 nm by soft X-ray irradiation. The electric resistivity of it also increased corresponding to the change of the surface roughness. Although the TO phonon peak was not observed for 1 nm-thick a-Si, it was observed for 50 nm-thick a-Si. For these phenomena, the mechanism that the electron excitation by photon becomes the trigger of the cohesion was discussed.