Epitaxial Preparation And Photoelectric Detection Of Two-dimensional Layered Bi₂O₂Se Heterostructures

Semiconductor heterojunction is a basic component of modern electronic and optoelectronic devices,and heterostructure has been extensively studied in recent years.So far,the use of CVD method has been successful synthesis of many heterostructures,but due to the low concentration of carriers and low component mobility,the prepared heterojunction has low responsiveness,detection rate is not high,unstable in the air and other shortcomings,how to epitaxial heterojunction to design high-performance photodetector is still a great challenge.In recent years,a new 2D material discovered,Bi₂O₂Se,has been shown to have a typical narrow band gap,high carrier mobility,superior air stability and high switching ratio,showing great potential in electronic and optoelectronic applications.Therefore,it is a very meaningful topic to construct semiconductor heterojunction based on Bi₂O₂Se nanomaterials and explore ideas to improve their optoelectronic performance.This thesis focuses on growing high-quality Bi₂O₂Se materials by using the CVD method.From two-dimensional Bi₂O₂Se nanosheets to Bi₂O₂Se thin films.Importantly,a controlled synthesis strategy for novel heterostructures is proposed later in this thesis.Transmission electron microscopy demonstrated that the epitaxial relationship is[110]||[00]_??,Ultraviolet photoelectron spectroscopy（UPS）and Kelvin probe measurements show that type I heterostructures form at the interface of CsPbBr₃/Bi₂O₂Se and photon-generated carriers have a tendency to shift from CsPbBr₃to Bi₂O₂Se.Optical characterization shows that there is a strong photoluminescence quenching phenomenon in the heterogeneous structure region compared to the original Bi₂O₂Se nanosheets,indicating the presence of interlayer charge transfer at the interface of the heterostructure.Electrical experiments further show that the photoelectric performance of CsPbBr₃/Bi₂O₂Se heterojunction-based devices is enhanced compared to the original Bi₂O₂Se devices,and that the rapid rise and decay times are within microseconds.These results show that the direct extension of CsPbBr₃to Bi₂O₂Se nanosheets can improve the photoelectric performance of Bi₂O₂Se devices,which indicates that the heterostructure can be applied to high-performance optoelectronic devices or integrated photonic circuits,and the results of this thesis also provide a new idea for improving the performance of optoelectronic devices.