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

TL;DR

This paper presents a fabrication method for ultra-low dissipation silicon nanowire arrays with exceptional force sensitivity, optimized for scanning probe microscopy, enabling highly sensitive measurements at room temperature and cryogenic conditions.

Contribution

The authors developed a high-yield fabrication process for ultra-high aspect ratio silicon nanowires with record force sensitivity suitable for advanced SPM applications.

Findings

Force sensitivity of 9.7±0.4 aN/√Hz at room temperature

Force sensitivity of 500±20 zN/√Hz at 4 K

Nanowires patterned for optical access within 7 μm of substrate edge

Abstract

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 $9.7\pm0.4~\text{aN}/\sqrt{\text{Hz}}$ at room temperature and $500\pm20~\text{zN}/\sqrt{\text{Hz}}$ at 4 K. To facilitate their use in SPM, the SiNWs are patterned within $7~\mu\text{m}$ from the edge of the substrate, allowing convenient optical access for displacement detection.