Interface study of heteroepitaxial diamond films on silicon (001) substrates

Locally epitaxial diamond films on mirror-polished Si(001) substrates have been prepared by using surface-biasing pretreatment in a hot-filament chemical-vapor-deposition system in our laboratory. The diamond is in epitaxial alignment with the silicon substrate, with approximately diamond (001) parallel to Si(001) and the [110] directions of the epitaxial layer parallel to the silicon surface. High-resolution cross-sectional electron microscopy clearly shows that there are about 40 rows of carbon-atom planes on 25 rows of silicon-atom planes in the observed epitaxial interface. The dislocation density is very high in the interface, but the diamond (1{}11{}) planes are shown to be continuous across the interface with 7.3^∘{} towards [001]. The three components of dislocations that are formed at the interface are discussed. The interfacial tilting and azimuthal rotational misorientation are shown to come from these dislocations. The relationship between the tilting angles and high-misfit-dislocation density is analyzed.