Ultra-low dissipation patterned silicon nanowire arrays for scanning probe microscopy

In recent years, self-assembled semiconductor nanowires have been successfully used as ultra-sensitive cantilevers in a number of unique scanning probe microscopy (SPM) settings. We describe the fabrication of ultra-low dissipation patterned silicon nanowire (SiNW) arrays optimized for scanning probe applications. Our fabrication process produces, with high yield, ultra-high aspect ratio vertical SiNWs that exhibit exceptional force sensitivity. The highest sensitivity SiNWs have thermomechanical-noise limited force sensitivity of 9.7 ± 0.4 aN/√Hz at room temperature and 500 ± 20 zN/√Hz at 4 K. To facilitate their use in SPM, the SiNWs are patterned within 7 μm from the edge of the substrate, allowing convenient optical access for displacement detection.