THE MORPHOLOGY OF DIAMOND GROWN BY HOT-FILAMENT CHEMICAL-VAPOR-DEPOSITION

The effect on the growth morphology of changing methane concentration and substrate temperature has been studied in a hot filament chemical vapor deposition reactor. Methane concentration and substrate temperat ures were varied from 0.5 to 1.5% and 536 to 1140 degrees C, respectiv ely. The morphology produced has been quantified as the ratio of the r ate of growth in the [100] and [111] crystallographic directions, and the dependence of this ratio on growth parameters has been used to pro duce a morphology map for the hot filament system. The morphology map generated shows trends similar to those observed for microwave plasma depositions. In addition, the apparent growth rates in the [100] and [ 111] crystallographic directions have been determined in the region of 1 < alpha < 3. The growth rate in the [100] direction exhibits a shar p drop at temperatures where the crystal geometry is changing from oct ahedral to cube-octahedral, whereas the growth rate in the [111] direc tion exhibits a more gradual change with temperature. These effects ar e attributed to the temperature dependence of surface diffusion. (C) 1 998 Elsevier Science S.A.