Dependence of Stretch Length on Electrical Conductance and Electronic Structure of the Benzenedithiol Single Molecular Junction

摘要

We have investigated the current-voltage (I -V ) curves of the benzenedithiol (BDT) single molecular junction as a function of stretch length of the junction. The BDT single molecular junction was prepared with the nano fabricated Au electrodes using the mechanically controllable break junction (MCBJ). The conductance of the BDT single molecular junction gradually decreased with the stretching length of the junction. We analyzed the obtained I -V curves based on the two different models; the single channel model and the field emission model. Based on the single channel model, it was revealed that the decrease in conductance was mainly caused by the decreases in the metal-molecule coupling and that the HOMO approached to the Fermi level with the decrease in the electrode separation. The energy shift of the HOMO was supported by the analysis based on the field emission model.