Diamond growth enhancement in d.c. discharge CVD reactors. Effects of noble gas addition and pulsed mode application

Abstract

Using the developed two-dimensional model of a d.c. discharge CVD reactor we have examined two possibilities of diamond growth rate enhancement. The first deals with the noble gas addition to inlet hydrogen-methane reactive mixture of a d.c. discharge. The second deals with application of a pulsed d.c. discharge. In the model, heat and mass transfer, electrodynamics phenomena, plasma-chemical and surface kinetics have been taken into account in a self-consistent manner. The electron-molecule reaction rate coefficients in methane/hydrogen/noble gas mixtures are calculated by solving the Boltzmann equation. Our calculations show that the dilution of the CH 4 H 2 mixture with argon allows the input power to reduce substantially and to increase the tolerable CH 4 H 2 inlet ratio. Diamond growth rate in a pulsed discharge may be several times higher than in a continuous d.c. discharge with the same power input. The overall enhancement depends on the relationship between the pulsed width and pause time.