A 2-STAGE METHOD FOR GROWING LARGE SINGLE-CRYSTALS OF DIAMOND WITH HIGH-QUALITY

A novel method is reported for growing large single crystals of diamon d at high pressure and high temperature using a metallic solvent, by w hich high-quality crystals can be grown with a larger net growth rate. The growing space has a recess at its lower temperature side, and the seed crystal is located at the bottom of the recess. The seed grows t o fill the recess, and its extended top surface serves as a large seed for the second-stage growth. The main part of the crystals grown in t he second stage is found to have no or only few metallic inclusions wh en the size of the recess is selected appropriately. Experimental resu lts show that the growth rate is small for the first-stage growth with in the recess, but it becomes larger after the crystal grows out of th e recess. The diffusion field of carbon in the solvent is simulated by numerical calculation, and the results can reasonably explain this na ture of the growth process.