Preparation And Properties Of Ultraviolet Detectors Based On ZnO Nanocomposites

ZnO,as one of the most important direct wide bandgap semiconductor materials of II-VI family,has potential applications in environmental monitoring,medical treatment,biology,monitoring,and military communication etc due to its special characteristics of bandgap width.Compared with traditional photomultiplier tubes and silicon-based ultraviolet detectors,ZnO as one of the main materials of the third generation ultraviolet photoelectric detection has attracted grat attention.Due to its excellent performance and many advantages,it can effectively reduce costs and rely on valuable equipment.In order to obtain ultraviolet photodetectors with excellent light response and fast response speed.In this thesis,material morphology selection and structure design are discussed.Photoelectric properties of ultraviolet photodetectors based on ZnO with different morphologiesare fabricated and analyzed.In addition,heterojunction films are prepared by introducing g-C₃N₄ quantum dots（QDs）and reduced graphene oxide（rGO）into ZnO films.The electrodes were prepared by thermal evaporation on the surface of the heterojunction films,and their photoelectric properties were further studied.Present thesis provides an experimental reference for the further study of ZnO ultraviolet photodetectors.The innovation of this paper and the main results are as follows:1.ZnO thin films with different morphologies are prepared on interdigital electrodes using Al₂O₃ or flexible PI as substrate by spin-coating method.The effect of different morphologies on the photoelectric properties of ZnO thin films is explored.The performance of ZnO thin films with different morphologies is obtained,the performance of ZnO nanowires is the best,which is mainly due to the large specific surface area of one-dimensional nanowires and faster carrier migration.2.ZnO nanowire thin films were prepared on interdigital electrodes using flexible PI as substrate by spin-coating method,and then heterojunction thin films were prepared by spin-coating method by spin-coating g-C₃N₄ QDs solution.Compared with pure ZnO nanowires,the optical response rate of g-C₃N₄/ZnO has been increased by nearly 10 times,and the response speed has also been significantly improved.At the same time,it has good stability for flexible devices.3.ZnO nanowire thin films were prepared on interdigital electrodes using flexible PI as substrate by spin-coating.Then heterojunction thin films were prepared by spin-coating method by adding reductive graphene oxide（rGO）solution of several times.Finally,heterojunction photodetectors were constructed by thermal evaporation on the side of the heterojunction thin films.Compared with pure ZnO nanowires,the photoelectric response rate has been increased by nearly 4.5 times,and the response speed has been greatly improved.At the same time,it has good stability for flexible devices.