SBIR-STTR Award

Next-generation of synchrotron and Free-Electron Laser X-ray sources will increase the peak power by several orders of magnitude. Diamond single crystals optical elements are promising for these radiation sources, where X-ray intensity will become too severe for the other existing materials. Increased X-ray power density imposes very high demands on the purity and structural quality of diamond substrates. Presently, the availability of large size, high-crystallinity, and low-defect density diamond substrates is very limited. There are no suppliers at all in the United States to support this rapidly developing field of diamond X-ray optics applications for the next generation sources. We will develop an advanced microwave plasma-enhanced chemical vapor deposition MPE CVD) reactor system, which would allow for fabrication of the highest crystallinity and very low defect density single crystal diamond substrates. This unique technology will enable a growth large type IIa or better diffraction-grade crystals with improved thermo-conductivity characteristics and comparable crystallinity of the best available high-pressure high-temperature diamond samples. The innovation is based on recently patented Euclid’s MPE-CVD diamond reactor technology. In Phase I, we will determine all necessary means for MPE CVD reactor parameters and operation and design the system to satisfy crystals quality imposed by demand of next-generation synchrotron and FEL X-ray facilities. We model and design key elements of the CVD reactor, in particular a modified substrate holder, for optimal SC diamond growth. In parallel we develop a growth strategy that expands the size of the seed crystal while minimizing strain and dislocation density using numerical modeling. We will also obtain extremely high-quality diamond seeds and prepare ultra-smooth surfaces needed for epitaxial growth. Material characterization before and after surface preparation will be conducted at APS ANL facilities using white-beam X-ray topography, sequential rocking curve mapping, high- resolution x-ray diffraction measurements. The technology developed here is required to utilize X-ray beams at fourth generation light sources to maximum potential. High-quality diamond is virtually the only material that can withstand the heat load of the next generation light sources. If a manufacturing technology for large size CVD diamond substrate is established, diamond-based optical elements will supersede the current silicon and beryllium alternatives, which have lower performance and severe health and safety concerns. High-quality diamond material will also benefit quantum computing, industrial, medical, and other industrial applications.

Large, diffraction grade single crystal diamond plates are needed for high power synchrotron and Free- Electron Laser (FEL) sources to enable the next generation of x-ray sources and experimentation. The current materials used cannot handle the heat loads and radiation intensity anticipated. Currently, there are no manufacturers of such material in the US. We propose the growth of high-quality single-crystal diamonds in the laboratory by chemical vapor deposition (CVD). The CVD technique does not suffer by the size limitations of other synthesis methods and can produce material with the highest purity, thermal conductivity, and radiation hardness available. Euclid Techlabs has designed a growth strategy to produce diffraction grade diamond plates with the desired material properties. In Phase 1, we have developed strategies for growing high quality, low strain, and dislocation material, which eventually can scale to larger sizes than diamond materials produced by other methods. Due to covid-19, single crystal diamond seed plates with significant areas (> 10 mm2) free of bulk defects arrived too late to properly prepare the surfaces, a critical part of the strategy. We were able to grow ca. 0.6 to 0.9 mm of epitaxial diamond on two initial plates (but not optimized to our strategy). Assessment of the quality of the epitaxial layers grown demonstrated areas as large as 1 mm2 with a very low strain-induced birefringence caused by defects implying low or no dislocations which is supported initial x-ray topography images. These results imply that we will be able to produce diffraction grade diamond by CVD.In Phase II, we will build our custom CVD reactor facility, acquire, and prepare appropriate diamond seed plates. Once the facility is operational, we will implement our growth strategy developed in Phase I for defect-free epitaxial CVD diamond single growth. To assist the development of the growth strategy, we will perform optical polarimetry, x-ray topography, x-ray rocking curve measurement, optical surface profilometry, photoluminescence, and other diagnostics as needed and appropriate. Finally, we will design and test preliminary prototype x-ray optical elements for commercialization. Enabling X-ray sources' high brightness will allow a new generation of measurements that could have a revolutionary impact across a broad area of science, including biology, medicine, cancer treatment, and quantum information.