LOW-TEMPERATURE GROWTH OF HIGHLY PURIFIED DIAMOND FILMS USING MICROWAVE PLASMA-ASSISTED CHEMICAL VAPOR-DEPOSITION

A variety of diamond films were synthesized in a microwave plasma of a CO-O2-H2 system by varying the O2 mole fraction. Then their properties were analysed by Raman spectroscopy and correlated with atomic hydrogen concentration in the plasma. The O2 additions were found to be effective for low temperature growth of high quality films as they ensured (1) a high concentration of atomic hydrogen in the gas phase, (2) a low concentration of acetylene in the gas phase and (3) efficient etching of amorphous hydrogenated carbon. It was confirmed that highly purified diamond films could be deposited even at 411-degrees-C in a 2.2% O2 system at a growth rate of 0.035-mu-m h-1. The full width at half-maximum of the diamond peak at 1333 cm-1 was 4.0 cm-1, which was extremely close to that of natural diamond.