CVD DIAMOND GROWTH MECHANISMS AS IDENTIFIED BY SURFACE-TOPOGRAPHY

The surface morphologies of numerous homoepitaxial, chemical-vapour-deposition-grown diamond films have been examined by phase-sensitive optical microscopy. The layers were produced by the hot filament technique as well as by the acetylene-oxygen combustion method. The {111} and {100} faces manifest themselves as F faces below the roughening temperature and grow via steps nucleated at three-dimensional diamond particles or at dislocations. The rate-determining step in {111} diamond growth is a hindered surface diffusion of the growth species towards the steps. The layer-by-layer growth on the {100} faces is discussed in terms of (2 x 1) surface reconstruction in combination with the presence of a 4, screw axis. The {113} face on flame-grown diamonds is made up of strong [110] chains of bonds which are interconnected by weak forces due to surface reconstruction. The slight curvature of this face points to an F face close to the roughening point. The {110} face is rough, i.e. K/S type, and no layer growth occurs. The different modes of crystal growth as well as local differences in step spacing are replicated as variations in the intensity of band A and 575 nm cathodoluminescence.