Investigation of diamond growth in a new planar microwave plasma source

Abstract

Low pressure diamond growth has been achieved with a planar microwave plasma source capable of creating very-large-area homogeneous planar microwave plasmas for chemical vapour deposition applications. The deposition experiments were carried out with mixtures of ethyl alcohol with hydrogen at flow rates of 370 standard cm 3 min -1, substrate temperatures between 600 and 800 °C and pressures near 2 kPa. With microwave power densities of approximately 20 W cm -2, average growth rates near 1 μm h -1 were achieved. The spatial structure of the plasma source can be described by an electrically and chemically active plasma layer near the quartz window, where the microwaves are coupled to the plasma, followed by a preferentially chemically active decaying plasma layer. The decaying chemical activity is mainly due to atomic hydrogen. This can be used to study the influence of different degrees of hydrogen dissociation on the diamond deposition.