DIAMOND SYNTHESIS BY MICROWAVE-PLASMA CHEMICAL-VAPOR-DEPOSITION USING CH3CL AND CH2CL2 AS CARBON SOURCE

Polycrystalline diamond films have been synthesized from gas mixture systems of CH2Cl2-H-2 and CH3Cl-H-2 by the microwave-plasma chemical vapor deposition (CVD) technique. The gas reaction speed was promoted by using CH3Cl and CH2Cl2, although the deposition rate decreased, due probably to surface etching by the chlorine in the case of high-concentration CH2Cl2. A broad band centered at about 1500 cm-1 in the Raman spectra decreased considerably in the films compared with those synthesized from the CH4-H-2 gas mixture. Very little residual chlorine was detected in the deposited films. The use of chlorine-permuted methane as a carbon source was found to be advantageous for high-purity diamond deposition at low temperature and high concentration.