Microscopic contact charging and dissipation

We investigated elementary processes of microscopic contact charging and charge dissipation on and in thin silicon oxide, using a reproducible and controllable contact charging method. As a result, we found that negative charges have three stages of contact charging and charge dissipation, while positive charges have only one stage. By continuing with the contact charging, negative charges became high density, i.e. a solid phase of charges, on the silicon oxide surface at room temperature in air. Furthermore, we succeeded in imaging point charges on n(+)-GaAs(110) cleaved surfaces with atomic resolution using a modified non-contact atomic force microscope. (C) 2001 Elsevier Science B.V. All rights reserved.