Electrical Characterization of Self-Assembled Monolayers
Electrical characterization of alkanethiol self-assembled monolayers (SAMs) has been performed using a nanometer-scale device structure. Temperature-variable current-voltage measurement is carried out to distinguish between different conduction mechanisms and temperature-independent transport characteristics are observed, revealing that tunneling is the dominant conduction mechanism of alkanethiols. Electronic transport through alkanethiol SAMs is further investigated with the technique of inelastic electron tunneling spectroscopy (IETS). The obtained IETS spectra exhibit characteristic vibrational signatures of the alkane molecules used, presenting direct evidence of the presence of molecular species in the device structure. Further investigation on the modulation broadening and thermal broadening of the spectral peaks yields intrinsic linewidths of different vibrational modes, which may give insight into molecular conformation and prove to be a powerful tool in future molecular transport characterization.