| Surface Plasmon Polariton(SPP)is a new research direction that combines the optical and electrical properties of matter at the nanoscale.Recently,a large number of optoelectronic nanodevices and nanostructures based on the principle of surface plasmon elements have been proposed to enhance the absorption by using the localized surface plasmon resonance(LSP)of metal nanoparticles.However,the quantum contact nanoswitches caused by the local plasmon thermal effect were first studied in this work.Mechanically Controllable Break Junction(MCBJ)was combined with local surface plasmon thermal effects,and a new technical means,light-controlled MCBJ,was proposed.Electronic switches with nanoscale dimensions meet the urgent demand for further device miniaturization.A recent,heavily investigated approach for nanoswitches is to use molecular junctions employing photochromic molecules that toggle between two distinct isoforms with different conductivities.In contrast to these reports,we demonstrated that the conductance switch behavior can be realized with only a bare metallic contact without any molecules under light illumination.We demonstrated that the conductance of bare metallic quantum contacts can be reversibly switched over eight orders of magnitude,far beyond the performance of molecular switches.After the switch process,the gap size between electrodes can be precisely adjusted with sub-angstrom accuracy by controlling the light intensity or polarization.Supported by simulations,we reveal a more general and straightforward mechanism for the nanoswitching behavior,i.e.,atomic switches can be realized by the expansion of nanoelectrodes due to plasmonic heating.The paper is mainly divided into the following contents.First,we realized the metal nano-optical antenna structure by mechanically controlled fracture technology(MCBJ)to form an adjustable nano-gap.The size of the gap can be indirectly characterized by conductance.At the same time,through scattering spectroscopy experiments,we observed different gap sizes corresponding to different positions of scattering peaks,verifying that local electric field enhancement exists between the nano-gap.Then,the influence of the intensity of the light intensity and the polarization direction on the conductance of the quantized contact and the conductance of the tunneling region is experimentally demonstrated.Based on the delay phenomenon of the conductance in the time domain with the change of the light intensity,the thesis proposes the effect of the thermal effect caused by the plasmon.Finally,the optical scattering module,the heat transfer module and the solid mechanics module in Comsol numerical simulation software were used for multi-physics coupling,which verified that the conductance switching phenomenon is caused by the nano-electrode localized enhanced electric field photothermal effect. |
