The Novel ZnO Nanowires Field Effect Transistor And UV Photodetector Based On Gas Ion Gate

Due to its large specific surface area and high surface activity,nanomaterials have high adsorption ability for gas molecules in air.Therefore,the gas adsorption at the nanomaterial surface/interface has a great influence on the properties of nanomaterials,such as catalysis,electrical transport,light detection,and gas sensing.Among them,the adsorbed gas ions at the solid/air interface are important for surface states.For example,the oxygen anions adsorbed on the surface of ZnO and TiO2 and their interface with metal,could be desorbed under the irradiation of ultraviolet light or in an atmosphere of reducing gas,which is the basis of light detecting and gas sensing.At the same time,these adsorbed oxygen anions are involved in the chemical reactions at the nanomaterial’s surface/interface,which is the basis of photocatalysis and electrocatalysis.At present,the methods for directly modulating the adsorption of ions at the solid/gas interface are still absent.This is mainly due to the fact that the existing instruments for ionizing gas are cost and have large size,which are difficult to combined with semiconductor nanoscale devices.In 2017,Professor Wang Zhong Lin’s group reported using the high voltage of triboelectric nanogenerator to produce quantified ions,which has been successfully applied as ionization power in gas-phase mass spectrometers.In 2018,our group also reported the ionization discharge characteristics of triboelectric nanogenerator in the air atmosphere.According to above background,we propose here the novel technology of the gas ion gate,which is based on the gas ions produced by the high voltage of triboelectric nanogenerator.It is demonstrated that,in this paper,the gas ion gate can be used to regulate the electrical transport properties of semiconductors,which can be applied to develop novel transistor and UV light photodetector with high performance.In the first chapter,we briefly review the research background and applications of different gate technologies for field effect transistors（FET）:the FET based on solid-state gate,the FET based on liquid ionic gate,and so on.The application of gas ions in the field of sensing and catalysis is highlighted.At the same time,it also focuses on the application of triboelectric nanogenerator for ionizing air into gas ions.The existed problems in the previous research have been discussed and the research proposal in this paper is put forward.In the second chapter,we established the novel technology of gas ion gate,which is based on triboelectric nanogenerator.It is demonstrated that the gas ion gate can be used to regulatie the ZnO nanowire film’s electrical transport characteristics,based on which the novel FET has been developed.At the same time,we investigated the effects of the amounts of O₂^-ions and the active surface site of ZnO nanowire on gas ion gate modulation properties.Then,the mechanism of the gas ion gate to regulate the electrical transport properties of the ZnO nanowire film was given,and the similarities and differences between the three gate modulation technologies were compared.In the third chapter,the gas ion gate was used to develop fast UV photodetectors of ZnO nanowire film.The gas ion gate was found to increase the on-off ratio and recovery speed of the original device.The on-off ratio was improved from 10⁴ to 10⁷,and the recovery time constant was reduced from 307 s to 0.32 s,which was increased by about 1000 times.At the same time,we demonstrated the gas ion gate can also be used under constant UV illumination condition,and the effect of gas ion O₂^-on adsorption equilibrium of oxygen and the recombination equilibrium of photogenerated electro-hole pairs was investigated.