Comparison of pulsed and CW regimes of MPACVD reactor operation

摘要

This work is a study of possible advantages of the pulsed regimes of microwave plasma-assisted CVD (MPACVD) reactor operation for diamond film synthesis. The influence of the pulsed regime as compared to the CW regime is studied with respect to changes in the deposition rate and changes in the temperature of the deposition surface. The results of two series of experiments in reactors based on a cylindrical cavity MPACVD reactor are presented. Results show a constant mean specific microwave power and constant substrate temperature in a thermally floating reactor configuration can be maintained in the pulsed regime by increasing the pressure as the duty cycle decreases.Furthermore, results indicate that at a fixed mean specific microwave power and substrate temperature the deposition rate increases in the pulsed regime as the pressure increases.Hence, for substrates that require a thermally floating reactor configuration (such as irregular-shaped, non-flat substrates and low thermal conductivity substrates, for which no active substrate cooling or heatin can be used) the pulsed regime can be used to increase the deposition pressure and hence the deposition rate without overheating the substrate.