Fabrication of Silver Scanning Tunneling Microscope Tips with Acetic Acid

Abstract

Scanning Tunneling Microscopy (STM) is used to image, manipulate, and spectroscopically characterize individual atoms and molecules to further develop an understanding of materials that have application in the semiconductor industry. The fabrication of sharp and smooth metallic tips plays an essential role in STM as the radius of curvature of tips used in STM directly influences resolution. The smaller the radius of curvature, the finer the resolution. We report a novel and reproducible fabrication procedure of silver STM tips. Silver wire is electrochemically etched using an environmentally benign electrolyte solution of volume ratio 1:8 glacial acetic acid: deionized water to form a tip radius of ~100 nm. Silver is used for its plasmonic enhancement of STM-luminescence and tip-enhanced Raman spectroscopy signals. The elemental purity and small radius of curvature (~100nm) of silver tips permits atomically resolved STM imaging, as well as photon emission and ultrafast electron emission measurements which will allow for better nano-scale understanding of a variety semiconductor materials.