The lateral outward growth of single-crystal diamonds by two different structures of microwave plasma reactor

Abstract

Using a semi-open holder, the homoepitaxial lateral growth of single-crystal diamond (SCD) was carried out via microwave plasma chemical vapor deposition (MPCVD). Via tuning and optimizing two different microwave plasma reactor structures, single-substrate and dual-substrate reactors, off-angles of 1.30–1.72° were self-formed on the diamond (001) crystal face. Then, SCD without a polycrystalline diamond rim can be synthesized in the different reactors. In the single-substrate reactor, the distribution of radicals was uniform and dispersed, which was suitable for the lateral expansion growth of SCD with smooth surface morphology and a low dislocation density. After 52 h of growth, the top surface of SCD grown in the single-substrate reactor expanded to 1.58 times that of the initial surface area. In the dual-substrate reactor, the intensity of carbon-related radicals increased significantly under the same process parameters. Furthermore, the lateral growth rate doubled in the dual-substrate reactor. The lateral surface of SCD grown in the dual-substrate reactor also displayed typical layered growth morphology with good uniformity and flatness. In addition, high-quality polycrystalline diamond film could be grown on the upper substrate via plate-to-plate MPCVD when using the dual-substrate set-up.