Probing the nature and resistance of the molecule–electrode contact in SAM-based junctions. Issue 28 (29th June 2015)

• Record Type: Journal Article
• Authors: Suchand Sangeeth, C. S.; Wan, Albert; Nijhuis, Christian A.
• Is Part Of: Nanoscale. Volume 7:Issue 28(2015)
• Page Start: 12061
• Page End: 12067
• Publication Date: 2015-06-29
• Subjects: Nanoscience -- Periodicals; Nanotechnology -- Periodicals; 620.505
• DOI: 10.1039/c5nr02570b
• Languages: English
• ISSNs: 2040-3364

Abstract

Abstract : For two-terminal molecular junctions composed of self-assembled monolayers (SAMs), the nature of the SAM–electrode interface is often unknown. Here we used potentiodynamic impedance spectroscopy to determine the nature and resistance of the SAM–electrode contact. Abstract : It is challenging to quantify the contact resistance and to determine the nature of the molecule–electrode contacts in molecular two-terminal junctions. Here we show that potentiodynamic and temperature dependent impedance measurements give insights into the nature of the SAM–electrode interface and other bottlenecks of charge transport (the capacitance of the SAM ( C SAM ) and the resistance of the SAM ( R SAM )), unlike DC methods, independently of each other. We found that the resistance of the top-electrode–SAM contact for junctions with the form of Ag TS –SC n //GaO x /EGaIn with n = 10, 12, 14, 16 or 18 is bias and temperature independent and hence Ohmic (non-rectifying) in nature, and is orders of magnitude smaller than R SAM . The C SAM and R SAM are independent of the temperature, indicating that the mechanism of charge transport in these SAM-based junctions is coherent tunneling and the charge carrier trapping at the interfaces is negligible.