VACUUM COMPATIBLE HIGH-SENSITIVE KELVIN PROBE FORCE MICROSCOPY

A vacuum compatible Kelvin probe force microscopy (KPFM) is presented. Difficulties in operating KPFM in a vacuum were overcome by utilizing the direct cantilever resonance frequency detection in the tip height control whereas the indirect resonance frequency detection scheme was used in primordial KPFM. The potential measurement sensitivity was im proved by 14 dB compared to that in air. It is due to the increased ca ntilever Q value and the reduction in the interference from the tip he ight detection signal because potential measurement is conducted using the cantilever's second resonance while tip height control was conduc ted using the first resonance. A silicon wafer whose surface is partia lly doped with arsenic by ion implantation was observed, and surface p otential difference at the junctions were clearly imaged. (C) 1996 Ame rican Institute of Physics.