Self-organized network structure appearing in the B/Si(111)-(√3x√3)R30° phase formation process studied by scanning tunneling microscopy

In the initial stage of the Si(111)-(root 3 x root 3)R30 degrees structural formation by HBO2 molecular irradiation onto a Si(111)-7 x 7 surface at similar to 750 degrees C, B atoms interacted with each other to form chains from the beginning, and a (root 3 x root 3)R30 degrees structure consisting of Si and B atoms was formed. The observed result is completely different from the (root 3 x root 3)R30 degrees structural processes induced by other group III atoms; in general, when metals such as Al are deposited on a Si(111)-7 x 7 surface, large 7 x 7 and (root 3 x root 3)R30 degrees structure domains exist separately. With an increase in the amount of the B component to about half the number of adatoms, B atoms formed a network with the same (root 3 x root 3)R30 degrees phase, resulting in the formation of an ordered (root 3 x root 3)R30 degrees structure. Off-phase disordered areas remaining on the surface were limited to the areas occupied by Si atoms. The obtained results indicate that the interaction caused by B atoms plays an essential role in the formation process of the ordered (root 3 x root 3)R30 degrees structure of this surface.