Fabrication Of Ultraviolet Sensors Based On Dielectric Manipulation Of ZnO Nanowires In A Conductive Island-based Microelectrode Sysetem

Ultraviolet sensor is a sensor for highly sensitive detection of ultraviolet radiation in electromagnetic waves.This kind of sensor is widely used in the fields of missile early warning,fire remote sensing,biochemical detection and confidential optical communication,so how to realize the rapid preparation of high-performance micro-ultraviolet sensors is important to the development of the above fields.The conductive island-based microelectrode system is an assembly system with a conductive structure between a pair of planar microelectrodes.This system can realize the parallel assembly of nanomaterials and provide an effective means for the rapid manufacture of ultraviolet sensors.To this end,this paper uses dielectrophoresis assembly technology to carry out a research on a nanowire ultraviolet sensor based on a conductive island-based microelectrode system.The specific content is as follows:First,the research on the preparation technology of the planar microelectrode system(the planar electrode pair system and the conductive island-based microelectrode system)was carried out.Based on the comparative analysis of the advantages and disadvantages of the planar microelectrode system prepared by the traditional photolithography process,it is proposed to use the electron beam Lift-off method to prepare the planar electrode pair system and the conductive island-based microelectrode system.This method can ensure high electrode shape accuracy and size accuracy,and provides an effective means for exciting the singular electric field to realize the directional control of the nanowires.Secondly,based on the theory of alternating current dynamics,this paper establishes a three-dimensional model of nanowire dielectric assembly based on a planar electrode pair system,and conducts theoretical and experimental analysis on the dielectric assembly process of nanowires at different frequencies.Under low-frequency assembly conditions,the nanowires are subjected to positive dielectrophoretic force.The dielectrophoretic force is the largest at the tips of the two electrodes.The alternating current electroosmosis flow can drive the nanowires to move to the assembly area.In the middle and high frequency areas,the alternating current phenomenon is manifested as alternating current electrothermal flow.When the driving frequency is further increased,the electrothermal flow reverses.Through the nanowire assembly experiment of the planar electrode pair system,it is found that at low frequencies,the nanowires can be assembled dielectrically into the electrode gap and connect the two tips of the electrodes.The electrodes have a poor ability to locate the nanowire,even near the electrode tips.There are still nanowires that cannot be assembled along the direction of the electrode tip connection;as the driving frequency increases,the number of nanowires that can be captured by the electrode pair decreases,and the positioning ability of the nanowire dielectric assembly in a planar electrode pair system is improved.Related research provides theoretical support and basis for the controllable assembly of nanowires in the planar electrode pair system.Thirdly,a multi-body dynamic model of the dielectric assembly behavior of nanowires in the conductive island microelectrode system was established,and the dielectric assembly regulations of nanowires at different frequencies were explored.The existence of the conductive island enhances the singularity of the electric field,especially the singular positions between the two electrodes.At low frequencies,nanowires undergo dielectric assembly under the combined action of dielectrophoretic force and electroosmotic flow.The dielectrophoretic force received by the nanowires in the near field determines the dielectric assembly behavior of the nanowires,while the electroosmotic flow in the far field is a more important aspect for the transport of nanowires.At medium and high frequencies,before and after the electrothermal flow is reversed,it can have different effects on the behavior of the nanowire dielectric assembly.The electrothermal flow direction is reversed to promote the nanowires to settle near the assembly area,and the reversal is more conducive to the assembly of the nanowires to the electrode and conductive island connection area.In the dielectric assembly experiment of nanowires,it was found that at low frequency,although a small part of nanowires can be assembled in the area connecting the electrode and the conductive island,a large number of nanowires are assembled in the nearby area.As the frequency increases to the mid-to-high frequency range,nanowires tend to be assembled in the direction of the connection between the electrode and the conductive island,and the positioning ability of the nanowires is further improved.This work laid a research foundation for the subsequent improvement of sensor performance.Finally,a nanowire UV sensor based on the conductive island-based microelectrode system was prepared,and the influence of the driving frequency of the dielectric assembly electric field on the comprehensive performance of the UV sensor was studied.The sensor’s detection current responds very quickly to ultraviolet light,and the improvement from dark current to photocurrent is significant,and the device detection result is highly stable.The goal of preparing an ultraviolet sensor with good comprehensive performance from the conductive island-based microelectrode system dielectrically controlled nanowires is realized.In summary,this paper establishes a dielectric assembly model of nanowires in the conductive island-based microelectrode system,conducts nanowire dielectric assembly experiments,and studies the influence of AC electrodynamic phenomena on nanowire dielectric assembly.A UV sensor based on the nanowire dielectric control of the conductive island-based microelectrode system was prepared.This sensor provides an effective way for the manufacture of high-performance UV sensors.