Synthesis of multiple single crystal diamonds by DC-GD-CVD

Abstract

Multiple single crystal diamonds (SCDs) were first synthesised on 24 high pressure high temperature (HPHT) synthetic type Ib (100) SCD seeds by direct current glow discharge plasma chemical vapour deposition (DC-GD-CVD) system with gas mixture of CH₄–H₂–Ar. Owing to the increase of the formed plasma density and temperature caused by the addition of 1.2 vol.-% Ar gas, a high growth rate of 22.2 µm h⁻¹ for diamonds deposition was achieved by the plasma with diameter of 2 inches at 900–950°C. After deposition for 50 h, diamond material with a thickness of about 1 mm was uniformly deposited on each seed. The average FWHM value, hardness and transmittance of as-obtained SCDs were 3.2 cm⁻¹, 105 GPa and 69.4%, revealing the high quality of multiple SCDs fabricated by the DC-GD-CVD method.