Hillock-Free Homoepitaxial Diamond (100) Films Grown at High Methane Concentrations

Improved growth processes for homoepitaxial diamond films with high quality and flat surfaces have been presented. Growth hillocks leading to rough surfaces were almost perfectly suppressed under the new growth processes, where the substrate temperature was set to a particular region. The high quality in electronic states was evidenced by the fact that the homoepitaxial films with thicknesses up to 11 µm gave intense free-exciton recombination emissions in room-temperature cathodoluminescence spectra. It is concluded that lobe-shape marks appearing on the surface after an apparent lateral diamond growth came from defects left on the substrate surface. The origin of the apparent lateral growth observed is discussed in relation to an enhanced speed of the step edge growth at the substrate temperature elevated to ∼1000°C.