Investigations Of Quantum Effect In The Charge Transport Through Single-Molecule Junctions Using Mechanically Controllable Break Junction Technique

The miniaturization of silicon-based devices is approaching the physical limits.To explore the potential of molecular devices for electronics appplications,it is necessary to investigate the charge transport of electronic devices at the single-molecule scale.In this thesis,we have carried out two experimental studies using MCBJ technology and the results are as follows:1.Gating quantum interference effects by heteroatom dopingSince the charge transport of single-molecular devices no longer obeys Ohm's law,quantum interference effects cannot be ignored.We introduce the N atom into quantum interference OPE molecular system.The result of breaking junction experiments and DFT theoretical calculations indicate that the introduction of heteroatom can bring spatially separated conductance pathways to gate destructive quantum interference.2.The fabrication and charge transport investigations of carbon based molecular devicesCarbon based molecular devices are considered to be alternatives to silicon based electronic devices,it is very important to investgate the all-carbon electronics.Metal electrodes are often used to capture target molecules and construct molecular devices in breaking junctions,which have the disadvantages of atoms easily migration and narrower functional ranges.We use grapheme electrodes instead of metal electrodes and build a series of graphene/single-fullerene/graphene junctions by ?-? stacking.For the first time,the all-carbon electronics research has been developed to angstroms scale.It is found that different sizes and conjugative fullerenes can tune electrical transport through the junction by bringing band gaps engineering.More interestingly,our work demonstrate that the doped heteroatom could introduce new resonance to tune the charge transport of the molecular junctions.These conclusions are confirmed by DFT calculation.This work indicate that the fullerene has the promising application for molecular electronics devices.