Abstrakt
The scanning tunneling microscopy is used to study morphology of a Tl adlayer in various stages of Tl desorption from the Si(111) surface. Transition from the Si(111)/(1 x 1)-Tl structure through the (root 3 x root 3)R30 degrees mosaic phase to domains of metastable Si reconstructions is observed.
Silicon substitutional atoms are found to be intrinsic to the (root 3 x root 3)R30 degrees structure. The temperature dependence of the amount of residual TI atoms on the surface is successfully fitted by a model using the first order desorption.
The same desorption energy of (2.1 +/- 0.3) eV and frequency prefactor 5 x 10(14 +/- 2) s(-1) during all stages of the desorption are sufficient for the fitting. It is concluded that bonding of Tl in both (1 x 1) and (root 3 x root 3) configurations is of the same nature.