Growth, structure and optical features of W/MG2Si multilayer X-ray mirrors

Abstract

Transmission electron microscopy and low-angle X-ray diffraction methods are used for investigations of W/Mg2Si multilayers structure. It is shown that due to interlayer interaction mixed zones of tungsten silicide are formed on the Mg2Si-W interface during deposition of W/Mg2Si multilayers. It is found that the composition of the mixed zones depends on thickness of the layers in X-ray mirror. In the W/Mg2Si multilayers with period of 3.1 nm the intermixed zones of tungsten silicide with the predominant content of tungsten namely W3Si and/or W5Si3, can be formed. In the multilayers with a period of 14.2 nm the composition of mixed zones is close to WSi2. Densities of mixed zones in multilayers with periods of 3.1 nm and 14.2 nm are 16.1 g/cm3 and 8.2 g/cm3 respectively. It is shown that reflectivity of the non-optimized in construction W/Mg2Si multilayer at wavelength of 9.89 nm is close to that of optimized W/B4C multilayer.