Hopping Transport through Self-Assembled Molecules: Transport Mechanism for Conduction-based Chemical Sensors

摘要

We have fabricated a testbed for hopping transport through a self-assembled monolayer (SAM), using a back-to-back schottky barrier structure on semi-insulating GaAs, and various molecules were self-assembled on the testbed. The leakage current of the testbed is less than InA. However, it was found that some of deposited molecules induce significant increase in conductivity, compared to pre-deposition current. There exist two possible conduction paths that might cause this phenomenon: I) hopping conduction through SAM 2) surface potential change due to SAM. To verify that the hopping transport is a dominant conduction mechanism, I-V characteristics of thiophenol and octadecanethiol have been compared to investigate the effects of molecular dipole moment and pai-electrons on conductivity enhancement. In addition, the application of the testbed to a chemical sensor has been demonstrated by depositing redox molecules on the testbed.