Study On The Preparation And Enhanced Ultraviolet Detection Effect Of Zinc Oxide Nanowires Networks

Ultraviolet detectors are widely used in various fields of science and technology,such as ultraviolet communication,atmospheric environment monitoring,fire prevention,ultraviolet astronomical observation,mineral and oil mining,the technology of ultraviolet countermeasures and anti-countermeasures,space technology,ultraviolet guidance and early warning systems,medical diagnosis and so on.With the continuous development of information technology,an ultraviolet detector with high sensitivity and fast optical response time is desired.There are many problems of traditional Ultraviolet detectors including low sensitivity,slow light response time,and complicated fabrication process.This paper is devoted to simplifying the fabrication process of ultraviolet detector and improving the optical response performance such as the sensitivity and response time of the ZnO nanowires ultraviolet detector.According to the periodic bond chain theory of crystal growth,the substrate of the ultraviolet detector is pretreated with the method of arrayed micro-pillars,and then the environmental parameters for the fabrication of ZnO nanowires are optimized.Finally,the zinc oxide nanowires are produced.The growth mechanism of ZnO nanowires is studied in detail.On the basis of the successful fabrication of nanowires,this paper uses oxygen plasma to etch the surface of the ZnO nanowires to improve the photoelectric performance of the single ZnO nanowire detector and studies the mechanism of oxygen plasma etching the surface of the ZnO nanowire.On the other hand,nanodiamond is used to modify the surface of ZnO nanowires networks to improve the optical response performance of ZnO nanowires networks photodetectors.Furthermore,the mechanism of nano diamond modified zinc oxide nanowire to improve the optical response performance is explored.In order to solve the problem that ZnO ultraviolet detector has poor detection effect for deep ultraviolet light due to the band gap of ZnO,this paper proposes a method of doping ZnO nanowires with Mg₃N₂.This method can be used to adjusting the band gap of ZnO nanowires in order to realize the effective detection of deep ultraviolet light.The dissertation has the following four innovative achievements:1.A method of preparation ZnO nanowires networks based on the array microcolumn is proposedIn order to avoid the catalyst contamination during the fabrication process of ZnO nanowires,a method based on the periodic bond chain theory is used to fabricate ZnO nanowires networks without catalyst.After pretreating the substrate of the ultraviolet detector with the method of arrayed micro-pillars,the lateral growth of ZnO nanowires networks is realized by the chemical vapor deposition method.This method can effectively solve the problem of catalyst contamination during the fabrication of nanowires,optimize the fabrication process and reduce the production cost.2.A method of oxygen plasma treated single ZnO nanowires is proposed to improve the photoelectronic performanceIn order to solve the problem of weak light signal of the single ZnO nanowire detector,the method of etching the surface of ZnO nanowire by oxygen plasma is proposed to improve the surface defect state of ZnO nanowire,and then improve its ultraviolet photoelectric response performance.After the oxygen plasma etching treatment,the photocurrent of the single ZnO nanowire detector is increased from 4.29μA to 27.2μA.The photocurrent is increased by 6.34 times.The response time in the rising stage is shortened from 0.27 s to 0.14 s.The measurement results shows that the photocurrent of single ZnO nanowire detector can be effectively improved by the oxygen plasma etching treatment.3.A method of modified ZnO nanowires networks with nanodiamond is proposed to improve the photoelectric performanceIn order to solve the problems of long optical response time and small photocurrent of ZnO nanowires networks photodetectors due to the long desorption and adsorption time of oxygen atoms on the ZnO nanowire surface,a method of coating the surface of ZnO nanowire with nanodiamond is proposed.The photocurrent of ZnO nanowires networks detector was increased from 20.2μA to 327.9μA after the ZnO nanowire network was modified by nanodiamond.The photocurrent of the detector is increased by 16.3 times.The response time of the rising stage was shortened from 1.39 s to 0.73 s.The sensitivity of the detector is increased from0.36 A/W to 5.69 A/W.The test results show that this method can effectively improve the light response performance of ZnO nanowires networks detector.4.A method of Mg doped ZnO nanowires network is proposedIn order to solve the problem that the ZnO ultraviolet detectors are poor at detecting the deep ultraviolet light with wavelength less than 300 nm due to the band gap property of ZnO,a method of fabricating Mg doped ZnO nanowires by chemical vapor deposition using Mg₃N₂ as magnesium source is proposed.By adjusting the band gap of ZnO nanowires,the detection ability of ZnO ultraviolet detector is improved.Magnesium doped ZnO nanowires are tested by deep ultraviolet light with a wavelength of 254 nm.The photocurrent of the detector is increased from 0.02μA to 0.57μA,the response time of the rising stage is shortened from 4.26 s to1.74 s,and the sensitivity is increased from 0.13 A/W to 4.75 A/W.The test results show that the ZnO nanowires manufactured by magnesium doping have stronger detection ability for ultraviolet light.Based on the above research work,the ultraviolet detector based on ZnO nanowires network is prepared.The photocurrent of the detector is 327.9μA,the response time of rising edge is0.73 s,and the sensitivity is 5.69 A/W.The research work of this paper effectively solves the problems of low photocurrent and low sensitivity of ZnO ultraviolet photodetectors,which makes ZnO ultraviolet photodetectors hopeful to be used in small portable devices,environmental monitoring devices and wearable devices in the future.