Imaging of trapped charge in SiO2 and at the SiO2–Si interface

Charged defects in SiO2 and at the SiO2–Si(111) interface were imaged with a noncontact atomic force microscope. Electrons and holes trapped at interfacial Pb centers in n- and p-type samples were identified from simultaneously recorded Kelvin images. Limited trap occupancy, determined by the local, bias controlled Fermi level, and strong band bending lead to unusually sharp images of trapped charge.