The electronic origin of contrast reversal in bias-dependent STM images of nanolines

MacLeod, J.M., Miwa, R.H., Srivastava, G.P., & McLean, A.B. (2005) The electronic origin of contrast reversal in bias-dependent STM images of nanolines. Surface Science, 576(1-3), pp. 116-122.

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Abstract

Self-organized Bi lines that are only 1.5 nm wide can be grown without kinks or breaks on Si(0 0 1) surfaces to lengths of up to 500 nm. Constant-current topographical images of the lines, obtained with the scanning tunneling microscope, have a striking bias dependence. Although the lines appear darker than the Si terraces at biases below ≈∣1.2∣ V, the contrast reverses at biases above ≈∣1.5∣ V. Between these two ranges the lines and terraces are of comparable brightness. It has been suggested that this bias dependence may be due to the presence of a semiconductor-like energy gap within the line. Using ab initio calculations it is demonstrated that the energy gap is too small to explain the experimentally observed bias dependence. Consequently, at this time, there is no compelling explanation for this phenomenon. An alternative explanation is proposed that arises naturally from calculations of the tunneling current, using the Tersoff–Hamann approximation, and an examination of the electronic structure of the line.

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13 citations in Scopus
12 citations in Web of Science®
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ID Code: 89939
Item Type: Journal Article
Refereed: Yes
Keywords: Silicon; Bismuth; Density functional calculations; Scanning tunneling microscopy; Growth; Low index single crystal surfaces; Self-assembly; Surface electronic phenomena
DOI: 10.1016/j.susc.2004.11.045
ISSN: 0039-6028
Divisions: Current > Schools > School of Chemistry, Physics & Mechanical Engineering
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: Copyright 2004 Elsevier B.V.
Deposited On: 06 Apr 2016 23:55
Last Modified: 06 Apr 2016 23:55

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