Simulations of atomic force microscopy image “flickering” on a doped Si (111) 7x7 surface using real-space pseudopotential calculations.

Recently a “flickering” phenomena has been reported using atomic force microscopy (AFM) imaging applied to a heavily B doped Si (111) 7x7. The flickering corresponds to a brightening and dimming image of the Si adatoms as the AFM tip height is changed. We employ real-space pseudopotential-density functional theory calculations to address this phenomenon. We consider stable structures of B doped Si structures with and without a CO-functionalized AFM tip. We find a bistable configuration of the B doped Si system with the presence of CO tip, which may account for the observed image changes.