HPHT Growth and Modeling of High-quality Defect-free Diamond Crystals

Diamond substrates for next-generation quantum computation/metrology, power electronics, and X-ray optics applications require high-crystallinity crystals with minimal defects density. We developed the modified High-Pressure High-Temperature (HPHT) temperature gradient growth technology that allows growing the highest crystalline quality large diamond crystals with a dislocation density of fewer than 10 cm^-2. This near-equilibrium process is carried out under extreme conditions, where diamond single crystals are grown from a carbon solution in molten metal solvent (Fe, Ni, and Co and their alloys) under pressures in excess of 5 GPa and temperatures of 1,600 K and higher. Since there are no available diagnostics to directly monitor crystal growth in the HPHT cell, both indirect experimental growth monitoring and faithful models are needed to connect experimental outcomes to system design and process conditions. We present initial results from a collaboration that includes experimental growth carried out at the Euclid Beamlabs and two modeling efforts by the University of Minnesota and Fraunhofer IISB. X-ray white beam topography of grown crystals is also discussed. This two-fold approach provides rigorous tools to both understand growth in this system and to perform subsequent optimization of growth conditions. In particular, we aim to more fully understand the fundamental aspects of diamond nucleation and growth and identify process conditions that will achieve the highest crystalline quality in large diamond crystals.