Recent advances in ion-assisted growth of Cr/Sc multilayer X-ray mirrors for the water window
2002 (English)Conference paper (Refereed)
Cr/Sc multilayer X-ray mirrors intended for normal incidence reflection in the water window wavelength range, ?=[2.4-4.4nm], have been grown by ion-assisted sputter deposition and characterized using soft and hard X-ray reflectivity. By extracting low-energy ions, with energies, Eion, ranging from 9 to 113eV and with ion-to-metal flux ratios, F, between 0.76 and 23.1, from the sputtering plasma to the growing film, the nano-structure of the multilayer interfaces could be modified. A significantly increased soft X-ray reflectivity, using ?=3.374nm, for Cr/Sc multilayers with layer thicknesses in the range 0.4-2.8nm, was obtained when high ion-to-metal flux ratios, FCr=7.1 and FSc=23.1, and low energy ions, Eion=9eV, were used. An experimental reflectivity of 5.5% was obtained at 76° for a multilayer with 400 bi-layers. Simulations of the reflectivity data showed that the interface widths are <0.425nm. It could be concluded that roughness of low spatial frequency is reduced at lower ion energies than the high spatial frequency which was eliminated at the expense of intermixing at the interfaces at higher ion energies. The predicted performance of normal incidence multilayer mirrors grown at optimum conditions and designed for ?=3.374 and 3.115nm indicates possible reflectivities of 6.5% and 14%, respectively. © 2002 Elsevier Science Ltd. All rights reserved.
Place, publisher, year, edition, pages
2002. Vol. 68, no 3, 275-282 p.
Chromium, Ion-assisted growth, Multilayer, Scandium, Sputtering, Water window, X-ray mirror
Engineering and Technology
IdentifiersURN: urn:nbn:se:liu:diva-46853DOI: 10.1016/S0042-207X(02)00457-8OAI: oai:DiVA.org:liu-46853DiVA: diva2:267749