Comparative Study of Pd/B4C X-ray Multilayer Mirrors Fabricated by Magnetron Sputtering with Kr and Ar Gas
Hangjian Ni, Qiushi Huang, Genchang Liu, Runze Qi, Zhong Zhang, Xiuhong Li, Zhong‐Liang Li, Jie Wang, Zhanshan Wang
Abstract
Ultrathin Pd/B4C multilayers are suitable X-ray mirrors working at the photon energy region of 7–20 keV. To further improve the layer structure, Pd/B4C multilayers with a d-spacing of 2.5 nm were fabricated by magnetron sputtering using the heavy noble gas Kr and compared with the conventional ones fabricated by Ar. Although the Kr-sputtering process can work at a lower pressure, the interface width—especially the interface roughness—is a little larger than that made by Ar. A stronger polycrystallization and a lower content of sputter gas atoms were found in the Kr-made sample, which can be explained by the joint effect from less recoiled particles and lower sputtering pressure. A good reflectance of 68% of the Kr made multilayer was measured at 10 keV, which is only slightly lower than that of the Ar made sample (71%).