DEMONSTRATION OF A METHOD TO FABRICATE A LARGE-AREA DIAMOND SINGLE-CRYSTAL

A multi-step process to fabricate a diamond single crystal that is lar ger than the original, natural, commercially-obtained crystals is desc ribed. Starting with 3.0 mm X 3.0 mm X 0.25 mm, natural, type Ia C(100 ) crystals that have had their edges oriented to (010) and (001), we h ave successfully bonded two to a Si substrate in close proximity to ea ch other. Subsequent diamond homoepitaxy using plasma-enhanced chemica l vapor deposition of up to similar to 75 mu m thickness has enabled e pitaxial overgrowth to join the two diamonds. The topography was excel lent, and microRaman spectroscopy indicated only a 0.6 cm(-1) line bro adening (crystal degradation) at the joint. The creation of etch pits (via oxidizing flame) on the joined diamond surface indicated a higher defect density at the joint, but this more-defective region was const rained to within the dimensions of the original gap between the diamon d crystals. These results indicate that this process of epitaxial join ing of diamond single crystals has the potential to be scaled up to la rger area in order to fabricate a diamond single crystal of desired ar ea and reasonable crystal perfection.