A STUDY ON SURFACE MORPHOLOGIES OF (001) HOMOEPITAXIAL DIAMOND FILMS

A systematic study on surface morphologies of (001) homoepitaxial diam ond films prepared by microwave plasma-assisted chemical vapor deposit ion indicates that growth of these films strongly depends on depositio n parameters such as misorientation angles of substrates, methane conc entrations, and growth temperatures. With increasing the misorientatio n angles; the surface morphologies changed from growth hillocks to mac rosteps. Step-flow growth resulted in higher growth rates than hillock growth. These indicate that surface steps play a significant role in diamond growth. It is proposed that hillock growth occurs through two- dimensional nucleation on terraces when the density of surface steps i s low, while the step-flow growth proceeds along the [110] directions on the substrates with the high density of steps. Homoepitaxial growth at 1% CH4 produced macrosteps with the surface close to the single-do main structure, while at 2 and 6% CH4, growth hillocks and random grow th morphology occurred with the double-domain surface. The variation o f surface morphologies and structure with methane concentration is att ributed to lower mobility and shorter diffusion length of adsorbates o n the surface at higher methane concentrations. During the step-flow g rowth, step bunching was more apparent at a lower temperature of 875 t han at 1200 degrees C. Step-flow growth with the single-domain surface is believed to produce higher-quality films with fewer lattice defect s than other growth modes. It is likely that the step-flow growth is f avored by increasing the misorientation angles, lowering the methane c oncentrations, and increasing the growth temperatures.