Preparation Of Tellurium-based Thin Films And Photodetector Performance

Tellurium（Te）has proved to be a new type of topological Weyl semiconductor material,with unique anisotropic spiral chain crystal structure,narrow band gap band structure,good environmental stability,high carrier mobility and other excellent characteristics,and has great application potential in the field of photoelectric detection technology.The existing tellurene film synthesis technology has harsh requirements for equipment and environment,and how to achieve efficient,controllable and simple preparation of high-quality tellurene film needs to be further explored.In this thesis,the growth process of tellurium and tellurium-selenium composite films was systematically studied by physical vapor deposition,and the development of high-performance photoconductivity and heterojunction photodetectors for tellurium-based materials was realized.The specific research content is as follows:（1）Telurene films were prepared by physical vapor deposition,and the effects of deposition temperature on the growth quality of the films were studied.The results show that the film has good crystallinity and uniformity,and the photodetector based on tellurene film shows broad spectral detection ability and thermoelectric performance.A flexible tellurene thin-film photodetector was prepared with polyimide（PI）as the substrate,and the device had stable photoelectric performance after multiple bending.（2）Se_xTe_1-x crystals were synthesized by calcination,and Se_xTe_1-xcomposite films were prepared by vacuum thermal evaporation,and the material characterization showed that the films were dense and uniform,and the Se_0.22Te_0.78 films had the highest crystallinity and a notable concentration.A photodetector based on Se_0.22Te_0.78 thin film was prepared,and the device exhibited fast response characteristics（rise time 10μs,fall time 30μs）under 808 nm illumination,ms-order response speed in the 1310 nm communication band,and 3db bandwidth of the device was 3.3 k Hz,which can maintain stable and fast response at 5 k Hz.（3）Se_0.22Te_0.78 thin-film/Ga As heterojunction array devices were prepared on the substrate of n-type gallium arsenide（n-Ga As）,and the responsivity and specific detection rate of the devices under 650 nm illumination were 84.8 m A/W and 1.15×10⁹ Jones.The device showed a rise time of 30μs and a fall time of 50μs at 1310 nm,which is significantly improved compared to that of photoconductive devices.The heterojunction device exhibits a 3d B bandwidth of 40 k Hz and an increased response time of 10μs at 5k Hz.The photoelectric response characteristics of array devices have good uniformity,and finally the imaging application is studied.