MORPHOLOGY OF AN AS-GROWN SURFACE OF SIC - DETERMINATION OF STEP FLOWDIRECTION

By means of optical and scanning tunnelling microscopy it is shown tha t there exists a distinct difference in some features of step morpholo gy on the rounded and the flat faces of SiC platelets grown by the Ach eson method. Two different distributions of steps around obstacles hav e been found. One distribution exhibits perturbation of the step train s in the region which is situated along the down stairway next to an o bstacle while the other is situated in the region of the up stairway. As perturbation of the step trains always occurs ''behind'' an obstacl e, this indicates whether steps advance or shrink. The latter shows, i n rum, whether a surface grows or sublimes. Altogether the results of this study show that in the Acheson process the rounded faces of SiC p latelets grow, but on the flat faces sublimation dominates.