In-phase step wandering on Si(111) vicinal surfaces: Effect of direct current heating tilted from the step-down direction

In-phase step wandering (IPSW), a newly found step instability due to step-down dc heating on Si(111) vicinal surfaces [Jpn. J. Appl. Phys. 38, L308 (1999)], is studied in detail in the case of dc heating not parallel to the step-down direction, including the time evolution of IPSW. The nucleation and growth of IPSW regions and the reorientation of ridges of IPSW from the step-down direction to the current direction, resulting in the asymmetric wandering of individual steps, are observed. The effects of the current component parallel to the step-down direction and perpendicular to it (parallel to the step direction) are discussed. As a special case an effect of dc heating parallel to the step direction is also studied.