The electronic transport properties of the alkanethiol self-assembled monolayer (SAM) with various terminal groups on Au (111) surfaces have been investigated by the conducting atomic force microscopy (CAFM). The results show that the terminal group has obvious effect on the conductance of the SAMs. Combining the X-ray photoelectron spectrum (XPS) analysis and CAFM, we have further studied the relationship between the conductance of SAM and the C1s binding energy of the terminal group of the molecule. It is found that the higher the binding energy, the lower the conductance of the SAM. We attribute this behavior to that the high binding energy would induce strong electronic localization in the terminal group of alkanethiol molecule, which results in raising the effective barrier of the electron injecting into the molecular chains and reducing the transport ability of the electrons in the molecule. In addition, we also find that different group terminated SAMs have different surface potentials, which can shift the zero point of I-V curve of SAMs.
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