The Study Of Transistor Optoelectronic Devices Based On The New 2D Semiconductor And Perovskite Materials

Photodetector has a wide range of applications in various fields,such as measurement,photometric measurement,infrared thermal imaging and remote sensing,etc.At present,as the size of electronic devices such as photodetectors continues to shrink,it is becoming more and more difficult to follow Moore's Law,and there is an increasing need for the replacement and transformation of new materials.Under this trend of device miniaturization,some two-dimensional(2D)materials have received widespread attention as promising replacements for existing semiconductor materials.Due to their excellent electronic and optoelectronic properties and suitable physical properties,many creative developments have been obtained.In particular,continuous breakthroughs have been made in transistors and light detection,greatly improving the electrical and photoelectric performance of the device.In this paper,the new 2D materials,perovskite materials,and their optoelectronic devices are investigated and summarized,and 2D InSe flakes,2D PdSe2 thin films,and CsPbBr3 films were selected to study the optoelectronic devices based on the new materials,and better performance was obtained,and the stability of the devices was improved.The main contents of the thesis include:In chapter 1,the research progresses on new 2D materials,perovskite materials,and their optoelectronic devices are summarized.The main research contents and innovations of the thesis are described.In chapter 2,the equipment used in the experiments and their roles in the study is introduced and explained.In chapter 3,the alternating phenomena of positive photoconductivity(PPC)and negative photoconductivity(NPC)in InSe photodetector were studied and analyzed.Multilayer InSe FETs were fabricated through mechanical exfoliation and microfabrication processes.By changing gate voltage(Vgs)and source-drain voltage(Vds),it is found that the phenomenon of PPC and NPC can be tuned in the multilayer InSe FETs.Combining with the experimental results,we gave a theoretical analysis and explained this phenomenon.It's well known that 2D InSe materials are very sensitive to environmental molecules due to their high specific surface area,which leads to changes in the performance of materials and devices exposed to air.The trap states formed on the InSe material top surface by adsorption water vapor and oxygen in the air is the main reason for the NPC.Based on the experimental results and theoretical analysis,we used PMMA encapsulated devices to avoid the occurrence of NPC phenomenon in InSe FETs,and the experimental results show that this is a feasible method.Our results provide a valuable strategy for the fabrication of stable multilayer InSe optoelectronic devices,as well as other 2D material devices.The mechanism of NPC in InSe FETs and the feasible method of NPC elimination can also be applied to other novel devices,such as photodetectors,optical switches,non-volatile memory,etc.In chapter 4,a novel CsPbBr3/HfO2/Si heterostructure device with high photoelectronic performance was proposed.The device is fabricated by using ALD deposited thin HfO2 layer and a simple CsPbBr3 colloidal drop coating process.Compared with the CsPbBr3/SiO2/Si device,the photocurrent enhancement of the CsPbBr3/HfO2/Si heterostructure device can reach about 5 orders of magnitude,with a responsivity of 45.05 A W-1,a detectivity of 9.12×1010 Jones,and External Quantum Efficiency(EQE)of 12445%,and the rise/fall time is 600 ?s/300 ?s.We reasoned that the improved performance of CsPbBr3/Hf02/Si heterostructure optoelectronic devices is attributed to the tunneling effect between CsPbBr3 and Si through the 20 nm thin Hf02 layer.More importantly,the photoelectronic properties of CsPbBr3/HfO2/Si heterostructure devices can be modulated by Vds and Vgs,which provides flexibility for different applications.This work will provide a new strategy for the preparation of high?performance CsPbBr3 optoelectronic devices,which may expand the applications of other perovskite devices and heterostructure devices,such as photovoltaic devices,optically pumped lasers,and solar cells.In chapter 5,the growth of large-area and uniform PtS2 film on different substrates by modified chemical vapor deposition(CVD)method and its application for photodetectors were studied.By comparing the qualities of PtS2 films on different substrates,it is found that the quality of PtS2 films grown on sapphire is better than that grown on Si/SiO2,which is also proved by the optoelectronic performance of the devices.The detectivity of the PtS2 device on sapphire can reach 9.17×109 Jones and the responsivity is 0.31 A W-1,but the response speed still needs to be further improved.The results provide valuable strategies for the growth of large-scale PtS2 films and the fabrication of stable PtS2-based photodetectors,though the mechanism of the synthesis of PtS2 films on different substrates still needs more research and experimental verification.Finally,the conclusions and prospectives of the thesis are summarized.The thesis provides valuable ideas for the application of new 2D materials and perovskite materials in the field of the photodetector.