Abstract
Using a scanning tunneling microscope, we have examined the effect of the bias voltage on the apparent barrier height. The sample used in this study was a nitrogen-doped lanthanum hexaboride film. We experimentally proved that a linear relationship exists between the apparent barrier height and the sample bias voltage. As a consequence, we estimated the work function of the film to be 2.35 eV by theoretical fitting. This value is in good agreement with that obtained by photoemission spectroscopy in a previous study. Our results demonstrate that the work function calculated through apparent barrier height measurements is guaranteed to be highly reliable in spite of the simple one-dimensional model. We anticipate that the sensitivity of the barrier height to the sample work function can be utilized for elemental identification on surfaces with characteristic work functions.
Highlights
Scanning tunneling microscopy (STM) is a tool for imaging surfaces at the atomic level
We anticipate that the sensitivity of the barrier height to the sample work function can be utilized for elemental identification on surfaces with characteristic work functions
Our results demonstrate that the work function obtained through apparent barrier height measurements is guaranteed to be highly reliable in spite of the simple one-dimensional model
Summary
Scanning tunneling microscopy (STM) is a tool for imaging surfaces at the atomic level. Instead, assuming a uniform potential, the effective barrier height affecting tunneling electrons can be calculated through I–z characteristics. This is called the apparent barrier height.[2] In other words, what is measured by STM is not the work function itself but the apparent barrier height.[3] The apparent barrier height depends on the work functions of the tip and sample and on the bias voltage applied between them. We experimentally proved the existence of a linear relationship between the apparent barrier height and the bias voltage, whose slope was in good agreement with the theoretical prediction of 0.5 eV/V.6. We anticipate that the sensitivity of the barrier height to the sample work function can be utilized for elemental identification on surfaces with characteristic work functions
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
