Faster simulations of step bunching during anisotropic etching: formation of zigzag structures on Si(1 1 0)

We propose that the formation of zigzag structures on Si(1 1 0) during anisotropic etching is mainly a result of the formation of inhomogeneous regions in the etchant due to diffusion phenomena. In the same way as the presence of these etchant inhomogeneities results in step bunches on miscut (1 1 1) surfaces, it results in zigzags on the (1 1 0) surface. To support this proposal, we present an incremental activity monitoring (IAM) method for the simulation of step bunching using a kinetic Monte Carlo scheme. For stepped (1 1 1) surfaces, comparison with a previous step density monitoring (SDM) method shows that IAM is typically faster by one order of magnitude and is well suited for the simulation of step bunching. By applying IAM to (1 1 0), the formation of zigzag structures can be simulated, strongly suggesting that the morphology of this surface is dominated by the formation of inhomogeneous regions close to the surface in the etchant phase.