Characterization of thin films for X-ray and neutron waveguiding by X-ray reflectivity and atomic force microscopy

Abstract

Phone: þ61 3 9905 4932, Fax: þ61 3 9905 3637 X-ray and neutron guiding in thin-film waveguides are finding numerous applications, such as sub-micron beam production for X-ray microscopy, and applications in neutron interferometric devices and polarizers. Thin-film waveguides are composed of a three-layer stack where the central layer, displaying low absorption for X-rays/neutrons, act as a guiding film. The utilization of such systems with low brilliance X-rays and neutron sources, requires the thickness of the guiding film to be increased. The efficiency of the waveguides critically depends on the thickness of the guiding layer and its surface roughness. In this paper we address the problem of producing relatively thick and smooth guiding layers for a high efficiency, thin-film neutron waveguide. We have produced a Ni/Al/Ni trilayer structure with a 500 nm thick Al layer optimized for neutron waveguiding. The characterization is performed by complementary X-ray reflectometry and atomic force microscopy. The surface roughness estimation by mean of the two methods is presented and discussed. We show that a combination of sputtering/evaporation processes is beneficial in reducing the roughness of the Al film.

Surface and interface characterization of Ru/C/Ru trilayer structure using grazing incidence X‐ray reflectivity and X‐ray fluorescence

“…and interface characterization of multilayered thin film samples having sufficient electron density contrast and thicknesses more than few nanometres. 2,3 In XRR measurements, beam intensity reflected from a sample is measured as a function of grazing incidence angle. As the reflected intensity is proportional to electron density contrast between different layers, therefore, XRR provides electron density versus depth information of layered system in direction perpendicular to the sample surface.…”

Advanced x-ray multilayer waveguide optics

“…An incoming beam is coupled in front of the structure, guided within a guiding layer of length L, and then coupled out in the exit plane. In this section, we will discuss a different coupling method, the resonant beam couplers (RBCs) [35,[42][43][44]. The guided modes are resonantly excited by shining a parallel beam onto the waveguide under grazing incidence using a precisely controlled incidence angle α i for each guiding mode.…”

“…Two different geometries are typically used to couple a synchrotron beam into a waveguide. Either the front coupling scheme, where the beam is coupled through the front face directly into the guiding layer [25,27], or the resonant beam coupling (RBC) scheme, where the beam enters from the side through a thinned cladding, usually the top face [35,[42][43][44]. In this case, the guided modes are resonantly excited by shining a parallel beam onto the waveguide under grazing incidence using a precisely controlled incidence angle α i for each modes.…”

Effect of Additive Glycerol on Piezoelectric Properties of Modified Sol-Gel (Ba_0.85Ca_0.15)(Ti_0.9Zr_0.1)O₃Ceramics

“…Therefore, it is essentially important to optimize the fabrication process through adjusting the complicated microstructure and composition to ensure high piezoelectric performances [10][11][12][13][14][15]. In this context, a few approaches have been reported, such as using different fabrication techniques, such as synthesizing high quality BCTZ powders by sol-gel process [10][11][12] and conventional solid state reaction method [13,14], optimizing the poling procedures [11,16], and grain size engineering [17][18][19][20]. There is still an unambiguous relationship between microstructure and properties of any material directly influence its properties.…”