The Fabrication And Performance Study Of Ultraviolet Detector Based On NaTaO₃ Composite

Ultraviolet detection technology is a military and civilian dualuse technology which has developed rapidly in recent years after microwave,millimeter wave and infrared detection technology.Due to some special properties of ultraviolet light in the process of propagation,it is very useful in military.At present,aircraft are powered by chemical energy,and there will be a lot of ultraviolet radiation in the plume,so ultraviolet detection technology is widely used in the field of monitoring and early warning.In the civil market,due to the large energy level gap between bonded and non bonded orbitals,UV detection plays an irreplaceable role in the detection of organic compounds,and is widely used in environmental detection,biochemistry and other fields.The materials used in UV detectors are wide band gap semiconductors,and the commonly used wide band gap semiconductors are difficult to be doped or produced,or need special processing technology.On the one hand,most wide band gap semiconductor materials are difficult to achieve ptype doping;On the other hand,most of the reported solar blind UV detectors need complex technology and expensive equipment,so the high manufacturing cost of UV detectors limits their application range.In this paper,NaTaO₃(NaTaO₃hereinafter referred to as NTO)wide band gap semiconductor material,which is easy to obtain,is selected as the core of solar blind ultraviolet photodetector by using simple material preparation processes such as hydrothermal method and spin coating method.The cost is reduced,the process is simplified,and the dependence of solar blind ultraviolet photodetector on equipment is weakened.Finally,a low-cost solar blind ultraviolet photodetector is prepared.In addition,the detection ability of NTO composite in near ultraviolet band was further explored.One of the research contents is the fabrication of nN heterojunction type NTO/TiO₂ solar blind UV detector element.TiO₂ thin film is prepared on FTO substrate by hydrothermal method.The granular NTO coated on TiO₂ thin film is transformed into NTO thin film by powder metallurgy process.After annealing,the NTO thin film and TiO₂ thin film are closely combined.Among them,NTO is used as photosensitive layer,TiO₂ is used as electrode,and the combination of NTO and TiO₂ is used as NN heterojunction,which improves the performance of the original single NTO UV detector.The electron transport model of NTO/TiO₂ heterostructure is established by theoretical derivation.Based on the thermodynamic statistics,the energy band distribution,barrier size and volt ampere characteristics of the junction interface of two ntype semiconductors with different materials are deduced.It is found that the builtin electric field only exists near the junction interface,and the barrier is very low and the junction capacitance is small,The voltage drop is mainly on the side with larger band gap.The volt ampere characteristics of the nN heterojunction show non rectifying characteristics.The results show that the dark current is only 70 pA,the ratio of light to dark current is 20,and the response time is less than 300 ms under 15V reverse bias.These test results are consistent with the results predicted by the electron transport model of the nN heterojunction.NTO/ZnO near ultraviolet photosensitive composite was prepared by hydrothermal method,and the NTO/ZnO Composite was successfully prepared,and the NTO/ZnO Composite was coated on the silver platinum electrode.It is found that the 1:1 NTO/ZnO Composite UV detector has the best comprehensive performance.Under 5V reverse bias,the dark current of NTO/ZnO Composite device is less than 1Na.Under the irradiation of 365 nmUV light with a power density of 56.5 mW/cm^2,the photocurrent of the photocell reaches 0.23?A.This shows that the combination of NTO and ZnO in the doping way expands the UV band that can be detected by nto materials,and further improves the application range of NTO materials.