High growth rate of 3-inch optical-grade polycrystalline diamond film via a novel 30 kW MPCVD reactor

Abstract Polycrystalline diamond materials face significant challenges in achieving large-area, high crystalline quality, and high growth rate simultaneously. In this work, a novel high-power 2.45GHz-30kW microwave plasma chemical vapor deposition (MPCVD) system is used to achieve high growth rate of optical-grade polycrystalline diamond films. By optimizing the substrate temperature and methane concentration systematically, a 3-inch free-standing polycrystalline diamond is successfully prepared with a growth rate of 3.5 μm/h and an infrared transmittance of approximately 70% in the wavelength range of 8-12 μm. These results confirm the feasibility of using high-power MPCVD system to alleviate the challenges posed by polycrystalline diamond.