Growth of permeable step bunches formed by drift of adatoms

We study bunching of permeable steps induced by drift of adatoms. In contrast to impermeable steps, bunching may occur with step-up drift. When diffusion length is short, terrace width between the bunches increases as L∝tβ with β≈1/2 through collision and coalescence. After the power law growth, the system reaches a steady state, where an array of similar bunches coexists with a few single steps on large terraces. If the diffusion length is long, the exponent β increases up to one.