REAL-TIME OBSERVATION OF (1X1)-(7X7) PHASE-TRANSITION ON VICINAL SI(111) SURFACES BY SCANNING-TUNNELING-MICROSCOPY

Scanning tunneling microscopy of a Si(111) surface with a misorientati on of 10-degrees reveals that the (7 x 7) domains form stripes whose w idths are quantized in units of a (7 x 7) unit cell. The (7 x 7)-to-(1 x 1) phase transition on this surface occurs at about 1030 K when the temperature is increased, which is about 80 K lower than that for a n ominally flat Si(111) surface, and the (1 x 1)-to-(7 x 7) phase transi tion occurs at 1003 K when the temperature is reduced. Nucleation and growth of (7 x 7) domains are explained in terms of the domains' energ y gain and the energy loss of the domain edges and slant surfaces.