New phase diagram of step instabilities on Si(111) vicinal surfaces induced by DC annealing

On Si(lll) vicinal surfaces, step bunching is observed when the sample is a nnealed with a direct current (DC). It is also known that the DC direction that induces step bunching changes three times with the increase of tempera ture. Recently it was found that; this step bunching instability takes plac e on Si(111) vicinal surfaces with off-angles up to 13-14 degrees [Jpn, J, Appl. Phys. 38 (1999) L308]. Temperature and off-ang le dependence of the s tep instabilities are studied. Results show that the transition depends on tile off-angle (mean step-step distance). It was also found that the off-an gle dependence for a step-down current and a step-up current differs.