Research On Self-driven RNiO₃/Nb-SrTiO₃?R=Nd,Pr? Heterojunction Ultraviolet Photodetectors

As a new detection technology,UV detection technology has strong anti-interference and anti-radiation properties,it becomes the focus of scientists' research.The rare earth nickelates RNiO₃?lanthanides other than La?have abundant physical properties and chemical properties,and the band gap of the perovskite RNiO₃ can be controlled by oxygen vacancies,enabling the RNiO₃ material to the wide spectral range photoelectric response and it is an ideal photodetector material.However,most studies on RNiO₃materials focus on the phase transition of MIT and the photoelectric conversion efficiency based on RNiO₃/Nb-SrTiO₃?RNO/NSTO?heterojunction.However,little research has been reported on the position detector.This paper has not only studied The vertical photovoltaic properties of the RNO/NSTO?R=Nd,Pr?heterojunctions also explore the lateral photovoltaic effect-related properties,further enriching the application of RNiO₃in photodetection.The main research content is as follows:Firstly,NdNiO₃?NNO?and PrNiO₃?PNO?thin films are prepared by pulsed laser deposition on STO substrates.The XRD,XPS,and TEM characterization tests showed that high quality NNO and PNO thin films were grown.The band of NNO and PNO thin films can be determined by light transmission spectra.Secondly,the self-driven NNO/NSTO heterojunction photodetectors are studied.The vertical IV curve shows that the NNO/NSTO heterojunction has unidirectional conductivity and forms a p-n junction.The presence of a built-in electric field contributes to the longitudinal separation of photocarriers and an open-circuit voltage of 0.4 V is obtained under light conditions,the longitudinal time-resolved test has a 1.8?s fast response time with external resistance.In the self-driven NNO/NSTO heterojunction lateral photovoltaic test,32 mV/mm position sensitivity and 7.4?s ultrafast time response are obtained.Through lateral I-V curves,it can be demonstrated that NNO and NSTO are ohmic contacts,and photogenerated carriers are mainly transmitted on the substrate.Finally,the self-driven PNO/NSTO heterojunction photodetector are studied.The vertical I-V curve indicates that the PNO/NSTO heterojunction has unidirectional conductivity and forms a p-n junction.The formation of the built-in electric field is the key to the study of the lateral photovoltaic effect,and an open-circuit voltage of 0.6 V is obtained under light conditions,indicating that the PNO/NSTO heterojunction has a self-driving effect and obtained an ultra-fast time response of 1.3?s in the longitudinal time-resolved test,indicating that the self-driven PNO/NSTO heterojunction has a good application prospect in the direction of UV photodetection and conversion.In the test of self-driven PNO/NSTO heterojunction lateral photovoltaics,the influence of film thickness and oxygen vacancy concentration on the lateral photovoltaic effect is explored,and the optimal growth thickness of the film 5 nm and the optimum oxygen pressure 1 Pa are found.The highest positional sensitivity of 28 mV/mm is obtained in the PNO/NSTO heterojunction.