  We use kinetic Monte Carlo simulations to understand growth- and
etching-induced step bunching of 6H-SiC{0001} vicinal surfaces oriented towards
[1-100] and [11-20]. By taking account of the different rates of surface
diffusion on three inequivalent terraces, we reproduce the experimentally
observed tendency for single bilayer height steps to bunch into half unit cell
height steps. By taking account of the different mobilities of steps with
different structures, we reproduce the experimentally observed tendency for
adjacent pairs of half unit cell height steps to bunch into full unit cell
height steps. A prediction of our simulations is that growth-induced and
etching-induced step bunching lead to different surface terminations for the
exposed terraces when full unit cell height steps are present.
