SBIR Phase I: X-Ray Focusing Device for 20-100 keV Photon Energies

This Small Business Innovation Research Phase I project targets the fabrication of X-ray focusing devices for high photon energies in the range from 10 keV to >100 keV, necessary for imaging, microtomography, and elemental and structural analyses of materials in spectral ranges and at resolutions unavailable today. Their primary use is in high-end synchrotron radiation facilities and in X-ray microscopes with X-ray tubes sources in specialized industrial and research environments. They form a special class of high-value consumables, with a functional life time of ~2.5 years, with capabilities to address the global market segment worth about $1M today for low and average performance diffractive focusing devices, to more than $4M, if the unprecedented performance devices will be developed. Availability of such focusing devices will enhance the scientific understanding of structure of matter at the nano-scale and the interplay of structure and functionality for applications ranging from drugs development to materials science, nano-electronics, biosciences, forensics, battery and energy research, investigating terrestrial soils or cosmic dust, the kinetics of ultra-fast chemical reactions, advanced catalysts, and others. The intellectual merit of this project is twofold. First, the innovative method of fabrication is a combination of top-down and bottom-up processing. It includes the atomic layer deposition onto batch-fabricated cylindrical silicon precursors of sequences of low and high absorption and refractive index materials, with well-controlled layer thicknesses varying from few nm to micrometers according to the Fresnel zone rules, followed by polishing the wafer to form membranes with focusing devices embedded into them. Hundreds of zone plates can be produced on one wafer, minimizing the processing costs per device. Second, the method is extendable towards depositing sequences of more-than-two material layers, which enables the fabrication of step-wise graded index kinoforms ? devices with single foci and of ultimate diffraction efficiency. Phase I will address these issues by effectively assessing the capabilities for individual key processes and will prove the fabrication feasibility, while Phase II will deal with the fabrication and testing of prototypes with long runs of atomic layer deposition processes, as necessary for functional devices.