Methods of fabricating synthetic diamond materials using microwave plasma activated chemical vapour deposition techniques and products obtained using said

摘要

A single crystal CVD diamond layer comprising a nitrogen content of 2 ppm or less when measured by SIMS and an area of at least 324 mm2. The layer which can be free standing has a thickness of at least 30 microns, comprises a plurality of inter-crossing dislocations and has an optical absorption coefficient of less than 0.09 cm-1 at 1.064 microns wavelength and less than 0.04 cm-1 at 10.6 microns wavelength. Also a single crystal CVD diamond which has substantially no orange luminescence from nitrogen-vacancy defects and substantially no blue luminescence from dislocations when viewed under photoluminescence. A diamond layer can be made on a substrate in a plasma chamber by forming a plasma in process gases including hydrogen and a carbon-source gas in the chamber using microwaves having a power density of at least 3 W/mm2 over a growth surface of at least 1962 mm2 for at least 24 hours.