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Molecular electron transport changes upon structural phase transitions in alkanethiol molecular junctions.
1National Creative Research Initiative, Center for Smart Molecular Memory, Electronics and Telecommunications Research Institute (ETRI), 161 Gajeong-dong, Yuseong-gu, Daejeon 305-350, Korea.
ACS Nano
|August 13, 2009
Summary
Structural phase transitions in thiolate self-assembled monolayers (SAMs) alter conductance. Changes in molecular coupling affect electron transport, impacting tunneling barrier height and decay constants in junctions.
Area of Science:
- Materials Science
- Surface Chemistry
- Nanotechnology
Background:
- Self-assembled monolayers (SAMs) are crucial for molecular electronics.
- Understanding conductance in SAMs depends on their structural phases and intermolecular coupling.
Purpose of the Study:
- To investigate the impact of structural phase transitions on conductance in thiolate SAMs.
- To analyze electron transport mechanisms in different junction types and SAM phases.
Main Methods:
- High-resolution scanning tunneling microscopy (STM) to observe structural phases.
- STM-based individual molecular junctions and micropore-based large molecular junctions for transport measurements.
- Analysis of tunneling barrier height and decay constants.
Main Results:
- Structural phase transitions (hexagonal to striped) observed in 1-octanethiol (OT) and 1,8-octanedithiol (ODT) SAMs.
- Electron transport in ODT SAMs showed higher sensitivity to phase transitions than OT SAMs.
- Phase transitions altered electron tunneling distances and barrier heights.
Conclusions:
- SAM structural phase transitions modify electron tunneling pathways (through-bond and through-space).
- Intermolecular coupling in large junctions significantly influences electron transport across different SAM phases.
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