Morphology and growth process of single crystalline diamond grown by microwave plasma CVD in the CO-H2 system

Single crystalline diamond was grown by microwave plasma CVD using a reactant gas mixture of the CO-H2 system. Spontaneously nucleated single crystals of diamond were deposited on silicon (100) wafer under conditions of 500 W microwave power (substrate temperature: 850-950 C), pressure of 30-60 Torr, and total flow rate of 200 ml/min. Euhedral diamond crystals having diameters of 5-20 microns were grown for 5 h under total pressure of less than 60 Torr, and at CO concentrations of less than 10 vol pct. The growth of (111) plane tended to prevail with increasing CO concentration. Variations of morphologies and growth process of coarse seed crystals of natural diamond (grain size of about 200 microns), which were placed on a silicon substrate, were observed at given intervals of reaction time under the above growth conditions.