The Physical Vapor Transport (PVT) process of SiC single crystal growth is characterized by a self-congruent process, which takes place at the surface of crystallization during the entire growth time of SiC. It is shown in this paper that in the self-congruent regime the growth rate depends on the crystal thickness and the heat transfer limitation plays a significant role starting form the initial stage of growth. Resulting from the self-congruent growth process, the crystallization temperature would asymptotically approach the temperature of the sublimating SiC source material when the crystal thickness reaches its top limit. In order to stabilize the growth rate, the crystal backside temperature has to be controlled in a certain manner, being a function of the crystal thickness, during the entire time of growth.