Variable temperature STM studies of the adsorption of oxygen on the Si(1 1 1)-7×7 surface

The scanning tunnelling microscope (STM) has been used to study the adsorption at room (300 K) and low (30 K) temperature of oxygen on the Si(1 1 1)-7×7 surface. Subsequently, STM manipulation has been used to find out which of the observed sites can be modified (displacement, transformation, desorption). It was found that the adsorption is quite different at 30 K compared to 300 K and that the manipulation at room temperature is essential in the identification of the sites. These results are in general agreement with recent conclusions from theoretical work [Phys. Rev. Lett. 84 (2000) 1724] and synchrotron radiation experiments [Phys. Rev. B 65 (2002) 035315].