Effect of environmental O-2 on the dynamical process of the Si(111)'1 x 1'-> 7 x 7 structural phase transition

The effect of environmental O-2 On the dynamical process of the Si(111)'1 x 1' --> 7 x 7 structural phase transition has been investigated. In a macro scopic view, growth of the 7 x 7 DBS structure on the quenched surface afte r pulsed laser irradiation was monitored in-situ with RHEED under different O-2 pressures. In an atomic scale view, the nxn DAS domain growth was obse rved with high temperature STILI. It has been found that the oxides formed in the '1 x 1' matrix or phase boundary between n x n DAS-1 x 1 and the n x n domain boundary is responsible for the suppression of the 7 x 7 growth. Under the higher O-2 pressure, not only suppression of the 7 x 7 growth, bu t also erosion of the 7 x 7 took place. The threshold O-2 pressure, which s uppresses the 7 x 7 domain growth but does not attack the 7 x 7 domains the mselves, was higher for the specimen kept at 600 degrees than that at 465 d egrees C because of fewer phase boundaries in the former. (C) 1999 Elsevier Science B.V. All rights reserved.