Scanning Enhancement of STM-tungsten Probes by Applying Colloidal Graphite Coatings

Tungsten cold field emission nanotips are known for their excellent performance as scanning tunneling microscopy (STM) probes. However, their performance is limited when the STM scan is performed in ambient gas pressure, or without insitu cleaning of the tip. As a reasonable solution for this problem, tungsten nano tip of 70 nm in diameter was coated by a thin layer of conductive graphite paint. The graphite paint was diluted by isopropanol to ensure the creation of a thin graphenic film on the nanotip apex. This process produced a tungsten-graphite composite probe of enhanced conductivity when compared to the oxidized tungsten tip, performing STM scans outside ultra-high vacuum environments.