  Growth of gallium nitride on GaN(0001) surface is modeled by Monte Carlo
method. Simulated growth is conducted in N-rich conditions, hence it is
controlled by Ga atoms surface diffusion. It is shown that dominating four-body
interactions of Ga atoms can cause step flow anisotropy. Kinetic Monte Carlo
simulations show that parallel steps with periodic boundary conditions form
double terrace structures, whereas initially V -shaped parallel step train
initially bends and then every second step moves forward, building regular,
stationary ordering as observed during MOVPE or HVPE growth of GaN layers.
These two phenomena recover surface meandered pair step pattern observed, since
1953, on many semiconductor surfaces, such as SiC, Si or GaN. Change of terrace
width or step orientation particle diffusion jump barriers leads either to step
meandering or surface roughening. Additionally it is shown that step behavior
changes with the Schwoebel barrier height. Furthermore, simulations under
conditions corresponding to very high external particle flux result in
triangular islands grown at the terraces. All structures, emerging in the
simulations, have their corresponding cases in the experimental results.
