Inkjet Printing Zinc Oxide Photodetector And Its Performance Optimization

Ultraviolet light detectors have wide application and development prospects in the fields of lighting,optical communication,national defense,aerospace and other fields.The third-generation novel semiconductor zinc oxide(Zn O)material is an important direct-gap semiconductor material with a wide band gap of group?-?.The band gap of Zn O is 3.37 e V.The exciton binding energy is as high as 60 me V,which is much greater than the thermal activation energy at room temperature of 26 me V.In addition,Zn O has good photoconductivity characteristics,an optical gain coefficient of up to 320cm^-1,strong absorption of ultraviolet light,and also has good piezoelectric and thermoelectric characteristics.Zn O is rich in raw materials,low cost,non-toxic Environmentally friendly.Therefore,as an important material for semiconductor ultraviolet optoelectronic devices,Zn O has important application potential in the field of electroluminescence and ultraviolet detection.This article uses an advanced 3D printing technology inkjet printing to print zinc oxide photodetectors.This is a new method.The characteristic of this method is that the production cost is very low;the preparation speed is fast;the material utilization rate is close to 100%;it can be completed at low temperature.In this paper,Zinc Oxide Nano powder was successfully configured as solute directly into ink,and a zinc oxide flexible photodetector based on polyimide was successfully printed.The main research contents of the paper are as follows:First,explore the preparation of zinc oxide ink using nano zinc oxide particles.After several experiments,We finally found N-methyl pyrrolidone(NMP)as the best ink solvent.NMP as a solvent has the following advantages,dissolving zinc oxide to the maximum;and it can be stored stably at low temperature;the solution is neutral.The successful configuration of zinc oxide ink greatly facilitates the printing of zinc oxideSecond,explore the effect of silver nanoparticles on the zinc oxide photodetector and its mechanism analysis.The 32 nm silver particles are printed on the surface of zinc oxide for modification by printing technology.Through the modification of silver nanoparticles,the deep-level and shallow-level defects are passivated,and the hydroxyl groups adsorbed on the surface are reduced.Passivation of shallow energy level defects reduces dark current;modification of silver nanoparticles stimulates plasmon effect,enhanced photon absorption,and improves current at illumination.Passivation of zinc oxide's oxygen vacancy defects,as well as reducing the adsorption of hydroxyl groups,thereby increasing the reaction speed of the device.Third,the effect of capping alumina on the zinc oxide photodetector was studied.Atomic layer vapor deposition is used to deposit alumina on zinc oxide.Experiments have found that after depositing an aluminum oxide layer,the surface leakage can be suppressed(dark current).This shows that alumina has passivated the shallow level defects.The decay time of the photodetector is also greatly reduced from 10.42 seconds to 1.51 seconds,indicating that aluminum oxide passivates the deep-level defects of zinc oxide,shortens the relaxation time,and improves the speed of the device.But the photocurrent and responsiveness have declined.Fourth,the effect of annealing on the capping alumina-zinc oxide photodetector was studied.After annealing,alumina can still passivate shallow level defects and reduce dark current.However,after annealing,the carbon impurities of aluminum oxide diffuse into the aluminum oxide layer and Zn O is doped in the form of carbon substituted oxygen.After doping,the absorption capacity of zinc oxide for photons is enhanced,so that the photocurrent and responsivity are improved by an order of magnitude.However,due to the introduction of new deep-level defects,the response speed of the device is reduced.