Electrical Charge Trapping at Defects on the Si(111)7x7 Surface

We report on a direct measurement of electron trapping at defects on the Si (111) 7×7 surface, by combining Kelvin probe force microscopy (KPFM) and scanning tunneling microscopy (STM) measurements. One-dimensional defects of atomic steps and two-dimensional defects of disordered domains were found on the surface. STM reveals that the disordered domain is located in the intersection area between three 7×7 domains. KPFM measurement shows that electrons are trapped at both the atomic steps and the disordered domains, and this electron trapping gives rise to a larger local work function on the defect region than on the defect-free 7×7 regions.