Advanced Surface Probing Using a Dual-Mode NSOM-AFM Silicon-Based Photosensor

A feasibility analysis is performed for the development and integration of a near-field scanning optical microscope (NSOM) tip-photodetector operating in the visible wavelength domain of an atomic force microscope (AFM) cantilever, involving simulation, processing, and measurement. The new tip-photodetector consists of a platinum-silicon truncated conical photodetector sharing a subwavelength aperture, and processing uses advanced nanotechnology tools on a commercial silicon cantilever. Such a combined device enables a dual-mode usage of both AFM and NSOM measurements when collecting the reflected light directly from the scanned surface, while having a more efficient light collection process. In addition to its quite simple fabrication process, it is demonstrated that the AFM tip on which the photodetector is processed remains operational (i.e., the AFM imaging capability is not altered by the process). The AFM-NSOM capability of the processed tip is presented, and preliminary results show that AFM capability is not significantly affected and there is an improvement in surface characterization in the scanning proof of concept.