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MI: Fachverband Mikrosonden
MI 6: X-ray Imaging, Holography and Tomography
MI 6.3: Talk
Wednesday, April 2, 2014, 11:30–11:45, MER 02
Multi-layer Fresnel zone plates towards high resolution soft and hard x-ray microscopy — •Umut Tunca Sanli1, Kahraman Keskinbora1, Corinne Grévent1, Marcel Mayer1, Adriana V. Szeghalmi2, Keith Gregorczyk3, Anna-Lena Robisch5, Tim Salditt5, Mato Knez3,4, and Gisela Schütz1 — 1MPI for Intelligent Systems — 2Friedrich-Schiller-University Jena — 3CIC nanoGUNE Consolider — 4IKERBASQUE Basque Foundation for Science — 5Institut für Röntgenphysik, Universität Göttingen
We fabricate full-material multi-layer Fresnel zone plates (ML-FZPs) by depositing alternating layers of high and low absorbing materials on glass fibers via Atomic Layer Deposition (ALD) followed by a slicing process with a Focused Ion Beam. Depending on their thicknesses the FZPs may be optimized to focus photons in a wide range from soft x-rays to gamma rays. We recently resolved 21 nm structures at 1 keV by direct imaging experiments. For hard x-rays, at 7.9 keV, Fourier analysis of the diffraction patterns gives clues about sub 30 nm resolution. The key to improve the resolution is to increase the Diffraction Efficiency (DE) in order to compensate for the efficiency losses associated with thinner zones. Our newest Al2O3-HfO2 FZPs are theoretically twice as efficient as our previous Al2O3-Ta2O5 FZPs at 1 keV and for dr = 11 nm. According to the coupled wave theory, the DE can be improved by 5 times by using commercially available materials for the ALD, such as Ir-Al2O3. It is expected, that the number of materials available with the ALD will increase allowing further improvement of the FZP performance.