Dual modulation STM: Simultaneous high-resolution mapping of the differential conductivity and local tunnel barrier height demonstrated on Au(111)

V. J.S. Oldenkotte*, F. J. Witmans, M. H. Siekman, P. L. de Boeij, K. Sotthewes, C. Castenmiller, M. D. Ackermann, J. M. Sturm, H. J.W. Zandvliet

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

We present a scanning tunneling microscopy (STM) technique to simultaneously measure the topography, the local tunnel barrier height (dI/dZ), and the differential conductivity (dI/dV). We modulate the voltage and tip piezo with small sinusoidal signals that exceed the cut-off frequency of the STM electronics and feed the tunneling current into two lock-in amplifiers (LIAs). We derive and follow a set of criteria for the modulation frequencies to avoid any interference between the LIA measurements. To validate the technique, we measure Friedel oscillations and the subtle tunnel barrier difference between the hcp and fcc stacked regions of the Au(111) herringbone reconstruction. Finally, we show that our method is also applicable to open feedback loop measurements by performing grid I(V) spectroscopy.

Original languageEnglish
Article number225301
JournalJournal of Applied Physics
Volume129
Issue number22
DOIs
Publication statusPublished - 14 Jun 2021

Fingerprint

Dive into the research topics of 'Dual modulation STM: Simultaneous high-resolution mapping of the differential conductivity and local tunnel barrier height demonstrated on Au(111)'. Together they form a unique fingerprint.

Cite this