STEP BAND STRUCTURES ON VICINAL SI(111) SURFACES CREATED BY DC RESISTIVE HEATING

DC-heating-induced step bunching is studied using vicinal Si(111) surfaces with different misorientation angles ranging from 1 to 10-degrees toward [112BAR] in an ultrahigh vacuum scanning electron microscope. Although the growth rate depends on the misorientation angle, the bunching structure basically grows in the same manner on the substrates misoriented from 1 to 8-degrees; faceting of the surface into (111) terrace regions and step band regions, and then expansion of terrace regions. The size of the initial facet structure correlates with the misorientation angle; the period of the structure is proportional to the misorientation angle. During heating, step band regions link up with each other forming very straight structures. Thus the surface with parallel step bands is the final form of the DC-heating-induced step bunching. The growth rate of the bunching on 1 and 2-degrees surfaces is much higher than on higher-misorientation-angle surfaces. On a 10-degrees misoriented surface no DC-heating-induced bunching was observed.