Study On The Preparation Of Two-dimensional Material Bi₂O₂Se And Its Photoelectric Properties

Two-dimensional(2D)nanomaterials show great application potential in high-performance optoelectronic,energy storage,catalysis and other electronic devices due to their ultra-thin atomic-level thickness,large specific surface area,adjustable energy band structure,high carrier mobility and higher integration.The emergence of graphene inspires the exploration of other graphene-like materials,such as black phosphorus and transition metal chalcogenides.The properties of 2D materials are closely related to their composition,structure,layer number and other factors.Therefore,the controllable preparation of 2D materials are the premise and basis for the development of their applications.Bi₂O₂Se is a novel 2D semiconductor material with high electron mobility,moderate band gap and excellent stability.It has a broad application prospect in the field of optoelectronics in the UV-Vis-NIR region.This paper mainly focuses on the following three aspects of the preparation and performance characterization of Bi₂O₂Se to carry out a comprehensive analysis and discussion,the main research content is as follows:(1)Bi₂O₂Se films are prepared by chemical vapor deposition:the effects of five factors on the growth of Bi₂O₂Se,including growth temperature,holding time,substrate position,flow rate and humidity,are discussed respectively.Finally,the better preparation conditionconditions of Bi₂O₂Se are obtained:high quality Bi₂O₂Se single crystal films with dimensions up to 200?m can be prepared when the growth temperature is 660?,the holding time is 30 min,the substrate is located at 20 cm downstream of the central high temperature zone and the flow rate is 100sccm.In addition,Bi₂O₂Se nanowires are successfully synthesized at low temperature.(2)Study on the transfer method of Bi₂O₂Se films:the transfer effects of Bi₂O₂Se films using Polyvinylpyrrolidone/Polyvinyl alcohol,Polymethylmethacrylate and Polystyrene as media are discussed respectively.The results show that the water-soluble PVP/PVA transfer method can cause the mica substrate to be torn and the Bi₂O₂Se films to be stripped by PVP/PVA at the same time,resulting in the failure of Bi₂O₂Se to attach to the target substrate.Large area Bi₂O₂Se films can be transferred by PMMA medium transfer method,but Bi₂O₂Se films are easily etched by HF,and it is very dangerous.PS has stronger adhesion and hydrophobicity than PMMA,and almost all Bi₂O₂Se films can be transferred with PS as the transfer medium,and the transferred Bi₂O₂Se films maintain high quality.(3)The photoconductivity detectors of Bi₂O₂Se on mica and Si/Si O₂ substrates are prepared and studied respectively.At room temperature,the photoconductivity detector based on Bi₂O₂Se film on mica substrate shows excellent photoelectric performance without gate voltage regulation.Its responsiveness,specific detection rate and optical gain are better than many other2D photoelectric devices,and can be compared with the best Bi₂O₂Se devices.Bi₂O₂Se nanowires and Bi₂O₂Se films transferred to Si/Si O₂ also show excellent photoelectric detection quality at high optical power density.