Surface potential mapping in the SiO₂ system using a FET cantilever

The surface potential variations are measured, according to the enhanced measuring speed and voltage sensitivity, using an active device, such as a field-effect-transistor (FET) [R.C. Barrett, C.F. Quate, J. Appl. Phys. 70 (1991) 2725; Y. Martin, D.W. Habraham, H.K. Wickramasighe, Appl. Phys. Lett. 52 (1988) 1103; G.H. Buh, H.J. Chung, Y. Kuk, Appl. Phys. Lett. 79 (2001) 2010]. In this study, the surface potential was mapped in the patterned SiO₂ medium at room temperature. An improved FET-tip cantilever, which has a source, a drain, and an n-channel, was used in this study. The potential images were analyzed both in the contact mode and the non-contact mode, using only a pre-amplifier system instead of a lock-in the amplifier. A probe was used to measure the surface potential with a resolution of <100 nm in the contact mode operation, based on the edge of the patterned SiO₂ islands. In the non-contact mode, however, the resolution of the surface potential was measured at about 270 nm at low scanning speed. The probe can also be used to write charges on a surface.