Kelvin probe microscopy of localized electric potentials induced in insulating materials by electron irradiation

Abstract

Kelvin probe microscopy (KPM) is a specialized atomic force microscopy technique in which long-range Coulomb forces between a conductive atomic force probe and a specimen enable the electrical potential at the surface of a specimen to be characterized with high spatial resolution. KPM has been used to characterize nonconductive materials following their exposure to stationary electron beam irradiation in a scanning electron microscope (SEM). Charged beam irradiation of poorly conducting materials results in the trapping of charge at either preexisting or irradiation-induced defects. The reproducible characteristic surface potentials associated with the trapped charge have been mapped using KPM. Potential profiles are calculated and compared with observed potential profiles giving insight into the charging processes and residual trapped charge distributions.