Deposition of diamond films with controlled nucleation and growth using hot filament CVD

Abstract

Abstract High quality diamond films have been deposited by sequentially switching between high and low oxygen feed to a hot filament CVD system with constant hydrogen and methane flow rates. Since a high oxygen feed is effective in etching non-diamond components in a growing diamond film, a computer can be used to control the switching between a high oxygen-content gas mixture, which is used for etching, and a low oxygen-content gas mixture, which is used for deposition, in order to achieve a higher growth rate of diamond deposition without sacrificing the diamond quality. SEM photographs and Raman spectra show that by decreasing the period of each cycling time, better diamond films are obtained. Using a cycling time of less than one minute, diamond films of the same high quality are deposited at a higher growth rate. A short cycling time is necessary to remove undesirable non-diamond components in time, in order to grow high quality diamond films at high rates by the hot filament CVD method. The high oxygen-content cycle of the CVD process reduces the density of secondary nucleation and leads to diamond films with larger grain sizes and clearer crystal facets.