STEP DYNAMICS ON HIGHLY ORIENTED AND VICINAL SURFACES OF SI(111)

By using high-temperature scanning tunneling microscopy we have measur ed step fluctuations on highly oriented and vicinal surfaces of Si(111 ) in the temperature range up to the (7 X 7)/(1 X 1) phase transition temperature (1100 K). On mono-layer steps these fluctuations mostly oc cur in a width corresponding to a 7 X 7 unit cell half. By an Arrheniu s plot of the fluctuation rate an activation energy for 7 X 7 kink dif fusion of 1.8 +/- 0.3 eV was estimated. On vicinal surfaces and just b elow the phase transition temperature fluctuations of entire 7 X 7 dom ains are observed.