Application of Solid-state High-power Microwave Source in MPCVD Reactor

¹ Institute of Plasma Physics, Chinese Academy of Sciences, Anhui Hefei 230021, China
² Hefei Fandao Electronic Technology Co., Ltd., Anhui Hefei 230061, China

^* Corresponding author: mwd@ipp.ac.cn

Published online: 7 January 2026

Abstract

Microwave Plasma Chemical Vapor Deposition (MPCVD) is the preferred method for producing high-grade diamond due to its electrode-free discharge and pure plasma advantages. With semiconductor advancements, demand for large-size optical-grade diamond is surging. 915 MHz MPCVD, offering 2-3 times larger deposition area than 2.45 GHz systems, is key for large-scale production. However, existing 915 MHz equipment relies on magnetrons, which suffer from high voltage, limited lifetime, and inflexible control. Solid-state microwave sources (low voltage, long lifespan, flexible control) are therefore attractive alternatives. While solid-state amplifiers with output powers of tens of kilowatts are already available in industry, reports at 915 MHz remain scarce, particularly in the context of MPCVD. In this work, we addressed challenges of multi-amplifier branch consistency and high-power radial combining, achieving stable 915 MHz/20 kW output. Preliminary plasma discharge has also been demonstrated, supporting the feasibility of developing large-scale diamond production equipment.