Development of the Advanced MPE CVD System for Growth of Large Diffraction Grade Single-Crystal Diamonds with the Exceptionally Low Density of Defects

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.