Effect of methane concentrations on surface morphologies and surface structures of (001) homoepitaxial diamond thin films

Homoepitaxial diamond films were grown on misoriented (001) substrates with CH4 concentrations of 1%, 2%, and 6% in H2. Reflection high-energy electron diffraction was used to characterize the surface structure. At 1% CH4, step-flow growth occurred with the surface close to the single-domain structure. This growth mode is expected to produce films with fewer crystal defects. On the other hand, when grown with 2% and 6% CH4, growth hillocks and random growth morphology were observed with the double-domain surface structure, respectively. The surface morphologies and surface structures are considered to change due to lower mobility and shorter diffusion lengths of adsorbates at higher CH4 concentrations.