Current–distance–voltage characteristics of electron tunneling through an electrochemical STM junction

• Published in: Surface science 2007-03, Vol.601 (6), p.1554-1559
• Main Authors: Woo, D-H., Choi, E-M., Yoon, Y-H., Kim, K-J., Jeon, I.C., Kang, H.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Electrochemistry; Electron tunneling; Exact sciences and technology; Gold electrode; Physics; Scanning tunneling microscopy (STM); Tunneling barrier height
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2007.01.021

We have studied the electron tunneling process through an electrochemical scanning tunneling microscopic (STM) junction formed by a gold tip and a gold electrode immersed in an inert NaClO 4 solution. Current–distance–voltage characteristics of the tunneling process are examined by simultaneous measurement of tunneling current, voltage, and distance. The results indicate that the tunneling voltage across the junction changes with tunneling distance; however, tunneling conductance is an inverse exponential function of distance over the entire investigated range of tunneling current, voltage, and distance. The results provide clear evidence for the validity of a one-dimensional tunneling model for the aqueous tunneling process. Implications of the observation are mentioned with regard to the distance-dependent STM imaging and the origin of a low tunneling barrier height.