Investigation of thick diamond films growth in different cvd reactors

Abstract

Summary form only given. For wide application of the CVD diamond in output windows of high-power microwave sources it is necessary to establish a CVD process for production of thick diamond films with controlled quality. Currently there are some microwave plasma CVD (MPACVD) reactors at 2.45 GHz frequency which may be used for this purpose. In our experiments polycrystalline high-quality diamond films were grown in a 6 kW industrial microwave plasma CVD reactor manufactured by AIXTRON company and in a pulsed MPACVD reactor with design developed in MSU. Influence of the total gas pressure from 130 to 200 mbar and the percentage of CH4 on the diamond growth on silicon wafers in the H2/CH4 gas mixture, as well as the influence of O2 addition on diamond quality in the H 2/CH4/O2 gas mixture has been investigated. The results of the growth of 0.1-2 mm thick diamond films 50-75 mm in diameter under these synthesis conditions are presented. The diamond quality was characterized using Raman spectroscopy and atomic force microscopy. The millimeter wave losses in the CVD films were investigated by using the installation on the base of a Fabry-Perot resonator in the frequency range of 50-300 GHz. Loss tangents of free-standing films were (1-2)middot10-5 at the frequency range 110-170 GHz. The mechanisms of microwave losses in CVD films are discussed