High-Rate Growth and Nitrogen Distribution in Homoepitaxial Chemical Vapour Deposited Single-crystal Diamond

High rate （〉 50 μm/h） growth of homoepitaxial single-crystal diamond （SCD） is carried out by microwave plasma chemical vapour deposition （MPCVD） with added nitrogen in the reactant gases of methane and hydrogen, using a polyerystalline-CVD-diamond-film-made seed holder. Photolumineseenee results indicate that the nitrogen concentration is spatially inhomogeneous in a large scale, either on the top surface or in the bulk of those as-grown SCDs. The presence of N-distribution is attributed to the facts： （i） a difference in N-incorporation efficiency and （ii） N-diffusion, resulting from the local growth temperatures changed during the high-rate deposition process. In addition, the formed nitrogen-vacancy eentres play a crucial role in N-diffusion through the growing crystal. Based on the N-distribution observed in the as-grown crystals, we propose a simple method to distinguish natural diamonds and man-made CVD SCDs. Finally, the disappearance of void defect on the top surface of SCDs is discussed to be related to a filling-in mechanism.