纳米厚度贫铀/Au多层膜的制备及特性研究

Preparation and characteristic study of nanometer thickness depleted uranium / Au multilayer

理论和实验研究表明,纳米厚度周期调制的贫铀(DU)/Au多层膜材料具有高效的激光X射线转换效率.采用交替磁控溅射制备纳米厚度的DU/Au平面多层周期结构,通过白光干涉仪、扫描电子显微镜、X射线光电子能谱对DU/Au多层膜的几何参数、表面形貌、成分以及界面形貌进行表征.实验结果表明:8 nm为Au连续成膜的厚度阈值,结合理论计算最优化原子配比,选取DU层厚度为30 nm、Au层厚度为8 nm的调制周期结构;实测周期厚度为37 nm;扫描电子显微镜照片显示DU/Au分层明显;X射线光电子能谱深度刻蚀分析表明DU/Au界面处存在扩散,DU,Au,O三者原子比为73:26:1;由于团簇效应,Au原子4f电子结合能向高能端移动,没有观察到DU相应的电子结合能移动现象.

Modeling and experimental results show that the depleted uranium （DU） and Au ＂cocktail＂ nanometer multilayer will improve the X-ray conversion efficiency by reducing energy loss to penetration of the X-ray into the hohlraum wall. DU/Au multilayer plane film is deposited by magnetron sputtering through alternately rotating substrate in front of separate DU and Au sources. The geometry parameter, surface topography, atomic concentration and interface structure of DU/Au multilayer are characterized by white light interferometer, scanning electronic microscope （SEM） and X-ray photoelectron spectroscopy （XPS）. Au film becomes continuous when its thickness reaches 8 nm. Combining with theoretical modeling results, 30 nm DU and 8 nm Au multilayer is chosen. The periodic thickness of DU/Au is measured to be about 37 nm. Well-defined Du/Au interface is observed by SEM. Diffusion at DU/Au interface is observed by XPS. The atomic concentration ratio of DU, Au, O is 73：26：1. The binding energy of Au 4f of 8 nm thickness Au film shifts toward high-energy tail about by 0.6 eV. Similar phenomena are unfound in 30 nm thickness DU film.