THERMAL DECAY OF SILICON ISLANDS AND CRATERS ON SILICON SURFACES BY SCANNING-TUNNELING-MICROSCOPY

Thermal decomposition processes of isolated silicon islands and fillin g-up processes of isolated craters on Si(111)7 x 7 surfaces are observ ed at various temperatures. By Arrhenius plots of rates of these size charges, activation energies for island decomposition and crater filli ng-up on the Si(111) surface are determined as (1.5 +/- 0.1) and (1.3 +/- 0.2) eV, respectively. Pre-exponential factors are 2.1 x 10(11 +/- 1) and 2.6 x 10(9 +/- 2) s(-1) for the islands and craters on the Si( 111) respectively. On the Si(111) surface the rates for island decompo sition are five times larger than those of craters filling up. We disc uss the results with two-dimensional vapor phase processes and the Sch woebel effect.