Abstract

It has been found that diamond can be grown at significantly lower substrate and filament temperatures by adding a small amount of oxygen to the mixture of CH₄ and H₂. In contrast to the insensitivity of the morphology to pressure in conventional HFCVD of diamond, pressure was found to have a significant effect on the diamond morphology in these low temperature deposition processes. At a fixed substrate temperature and CH₄ percentage in the feed gas, the morphology changed from cubo-octahedral to octahedral when the pressure was increased from 10 torr to 90 torr. The particle size also became increasingly non-uniform. The average growth rate saturated at about 20 torr. Changes in the relative concentrations of species such as methane and acetylene in the reactor were found to closely follow the trend of morphology change.

The mechanisms causing pressure to affect the morphology and uniformity under these deposition conditions are discussed in terms of gas phase and surface chemistry as well as growth mechanisms.

© 1995 Optical Society of America