Scanning tunneling microscopy with InAs nanowire tips

TL;DR

This paper demonstrates the use of InAs nanowires as tips for scanning tunneling microscopy, achieving high stability and minimal modification during imaging, with potential integration into circuitry.

Contribution

It introduces a novel method of fabricating STM tips from InAs nanowires with precise positioning and compatibility with integrated circuitry.

Findings

Achieved 2 pm z-noise and 0.5 nm lateral stability.

Observed exponential decay in I(z) spectroscopy indicating vacuum tunneling.

Nanowires remain minimally modified after STM imaging.

Abstract

Indium arsenide nanowires grown by selective-area vapor phase epitaxy are used as tips for scanning tunneling microscopy (STM). The STM tips are realized by positioning the wires manually on the corner of a double cleaved gallium arsenide wafer with submicrometer precision and contacting them lithographically, which is fully compatible with further integrated circuitry on the GaAs wafer. STM images show a z-noise of 2 pm and a lateral stability of, at least, 0.5 nm on a Au(111) surface. I(z) spectroscopy reveals an exponential decay indicating tunneling through vacuum. Subsequent electron microscopy images of the tip demonstrate that the wires are barely modified during the STM imaging.