High-quality homoepitaxial diamond films grown at normal deposition rates

High-quality homoepitaxial diamond films without any growth hillocks and ab normal particles have been successfully deposited at a reasonably high depo sition speed of similar to 0.5 mum/h by a 5 kW microwave plasma chemical va por deposition system. These films show cathodoluminescence (CL) spectra pr edominated by strong free-exciton recombination radiation assisted by a tra nsverse optical phonon and its replicas even at room temperature. The tempe rature dependence of the CL feature has been analyzed quantitatively. The r esults suggest that a considerable reduction of non-radiative relaxation pa ths is accomplished in the present case of high-quality diamond films.