2006 年 75 巻 4 号 p. 043601
We study the effect of two-dimensionality on step bunching on a Si(001) vicinal face heated by direct electric current. When the 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 wandering 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 experiment (Latyshev et al.: Appl. Surf. Sci. 130–132 (1998) 139). In a two-dimensional model with a wide system width, the step bunches wander heavily with step-up drift, and the recombination of neighboring bunches occurs more frequently than those with step-down drift. The bunching with step-up drift is accelerated and can be faster than that with step-down drift.