Study On Charge Transport Mechanism Based On Self-assembled Monolayer Molecular Junction Devices

Molecular-scale electronics studies the charge transport properties across molecules by constructing “electrode-molecule-electrode”junctions based on the molecular electrodes and single molecule or small amounts of molecular aggregates.It examines the structureproperty relationship between the physical and chemical properties of the molecule and the charge transport by combining the intrinsic chemical properties of molecule with device architecture,reveals the micro-scale quantum transport mechanics principle,and explores molecular-based functional electronic devices.It is a research field that integrates chemistry,physics and microelectronics.In recent years,molecular electronics has attracted more and more attention from scientists,which makes it to acquire new progress and achievements.In this work,we report the fabrication of molecular devices through forming both single and double self-assembled monolayers(SAM)between top and bottom gold electrodes using suspended nanowire technique.The current of prepared molecular junctions exhibited large increase and charge transport mechanism experienced a transition from pure tunneling mechanism to a combination of both tunneling and hopping mechanism upon coordination of copper ion with carboxylate acid groups in the SAMs,which introduced a redox active center into the molecular junctions.Our main results are demonstrated in the following chapters:Firstly,introduced the two mechanisms of tunneling and hopping charge transport in molecular junction devices,and the principles and methods of self-assembly and suspension nanowire technology used in the experiments.Secondly,self-assembled suspended nanowires were combined with coordination metal copper ions to prepare self-assembled monolayer device.The physicochemical properties of molecule in molecular junctions were characterized,and the electrical properties of the devices were analyzed and theoretically fitted.Study the properties of it's charge transport mechanism.Finally,double self-assembled molecular layer device with electroactive center was prepared by self-assembled suspended nanowire technology combined with coordination metal copper ions.The electrical transport characteristics and theoretical fitting of the device were used to investigate the change of charge transport mechanism..