2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/26568We study the effect of two-dimensionality on step bunching induced by drift of adatoms. When anisotropy of the diffusion coefficient changes alternately on consecutive terraces like a Si(001) vicinal face, bunching occurs with the drift of adatoms. If the fluctuation of step bunches is neglected as in the one-dimensional model, the bunching with step-down drift is faster than that with step-up drift in contradiction with the experiment by Latyshev and coworkers. In a two-dimensional model, the step bunches wander heavily with step-up drift and recombination with neighboring bunches occur more frequently than those with step-down drift and the bunching is accelerated. When the difference of kinetic coefficients between two types of steps is taken into account, the bunching with step-up drift can be faster than that with step-down drift.4 pages, 9 figuresMaterials Sciencetext