CVD Growth Method Of CsPbBr₃ Perovskite Material And Development Of Light Detector

Semiconductor photodetectors can convert modulated optical signals into corresponding electrical signals.Due to its high quantum efficiency and small size,it has been widely used in many fields such as optical communication,remote sensing,digital imaging,remote control,and biological research.As a rising star in the field of materials science in recent years,the all-inorganic perovskite material CsPbX₃ has a carrier diffusion distance of up to 175μm,10 times the absorption coefficient of organic dyes,a high level carrier mobility(1000 cm²V^-1s^-1)which is at the same level as Si materials,and a quantum yield of up to 95%.After one month of exposure to the atmosphere,its quantum yield did not decrease significantly.After 1.6×10⁷ laser irradiations,the luminous performance is still close to 90%.Compared with traditional semiconductor materials,perovskite is easier to rely on simple and economical experimental technology to achieve better material properties such as narrow emission spectrum and high absorption efficiency.These excellent characteristics make perovskite materials have broad application prospects in light-emitting diodes,laser gain media,and photodetectors,and make them be ideal functional materials for low-cost,low-voltage,high-performance next-generation detectors.The response wavelength of the CsPbX₃-based photodetector is in the visible light range,and has the advantage that the response wavelength can be adjusted by simple means to adjust the material band width.As a sensor,it is used in smart homes,the Internet of Things,wearable devices,and health management has huge application potential.The first choice for making all-inorganic perovskite-based photodetectors is thin film.The better method of preparing the thin film is a simple solution method.First,micro-nano materials such as nano crystals and nano flakes are prepared,and then spin-coated into a thin film or a self-assembled bulk material.At present,micro-nano structures are rarely mentioned for the researched perovskite-based detectors.But for micro-nano structures CsPbBr₃ detectors,a large surface area can enhance the performance of the detector.The traditional solution method is difficult to prepare micro-nano structure detectors.In view of these problems,this paper intends to use chemical vapor deposition（CVD）to solve them.The CVD method is an effective method for preparing traditional semiconductor（such as ZnO,GaAs etc.）single crystal thin films,and can effectively integrate semiconductors with various epitaxial substrates.So it is convenient for facilitating the design and fabrication of a variety of integrated devices with excellent performance.Therefore,it is necessary to carry out the research on the high quality CsPbX₃ thin film prepared by CVD.I use a mixture of PbBr₂ and CsBr₂ as raw materials,and use CVD to grow CsPbBr3 films on ITO to find the best growth conditions.In total,the following work was carried out:1.The chemical vapor deposition method is used to grow zinc oxide microwires with a cross-section diameter of 10-20μm and a length of 1.5 cm.By adjusting different temperatures and pressures,lengths of microwires are grown,so as to explore the optimal temperature and air flow for growing zinc oxide microwires.Below 1000 degrees,the zinc oxide microwire can not be grown.When the temperature is higher than 1100℃,carbon and oxygen in the raw material react sufficiently,and no microwire is formed.When the temperature is higher than 1000degrees and less than 1100 degrees,a proper carbothermal reduction reaction occurs in the raw materials,thereby generating zinc oxide microwires.Initial control of zinc oxide microwire length is achieved.2.The chemical vapor deposition method was used to grow the CsPbBr3perovskite thin film,and explored the best growth conditions,and constructed a Schottky junction photodetector.The device had good performance and good stability.3.Further,chemical vapor deposition method is used to construct a core-shell structure microwire,and cesium lead bromine is grown on the zinc oxide microwire.The zinc oxide microwire was used as the core layer,and the cesium lead bromine was used as the shell layer.The temperature was raised to 590℃at a temperature rising rate of 25℃/min to obtain a zinc oxide/cesium lead bromine core-shell microwire.The core-shell microwire detector was initially constructed,and FIB（Focused Ion Beam）technology was used to strip the cesium lead-bromine shell layer at one end of the zinc oxide/cesium lead-bromine core-shell microwire.A first metal electrode was prepared on the zinc oxide core layer exposed on one end and a second metal electrode was prepared on the cesium lead bromide shell layer on the other end by means of vacuum thermal evaporation.And the commercial 540 nm diode was used as the light source to test the detection performance of the device.