Surface atomic structure of Ag/Si(111)-√3X√3

Contrary to earlier reports, high-resolution scanning tunneling microscopy (STM) images of the Ag/Si(111)-root 3 x root 3 surface show an inequivalent honeycomb structure at room temperature. The appearance of two different sizes in Ag trimers fits well with a recently reported inequivalent-triangle model instead of the widely accepted honeycomb-chain-trimer model. In addition, we found that Si trimers, which were missing in earlier STM observations, form a bright hexagonal pattern surrounded by a honeycomb chain from Ag trimers.