Field emission for cantilever sensors

Abstract

Field emission provides an alternative sensing solution in scaled electromechanical systems and devices, when typical displacement detection techniques fail in submicron and nanodimenions. Apart from its independency from device dimension, it has also a high response, integration and high compatibility benefits. In this work, we propose using two modes of detection (fixed current and fixed bias) on two sensing methods: static sensing and dynamic resonance sensing. We measured the characteristic of the two modes and proved that field emission is a viable cantilever displacement detection technique. Customized tip on a fixed substrate has been fabricated and loaded to a UHV atomic force microscopy scanning tunneling microscopy system providing us a field emission environment with precise distance controls without the effects of cantilever bending. Thus, we are able to measure and determine the relationship of emission electric field to the electrode distance, as well as the relationship of the emission current to the electrode distance. The sensitivity obtained in our work for the static mode is 0.5V∕nm. In dynamic mode, we successfully measured a resonance of a piezoactuated cantilever at 162.2kHz. Characterizing these relations enabled us to propose the possibility of using field emission as a cantilever displacement sensing technique.