Preparation Of Two-dimensional Indium And Tin Based Chalcogenides And Structural Optimization Design Of Photodetectors

Two-dimensional Indium and Tin Based Chalcogenides,mainly represented by SnS,SnSe,InSe and In₂Se₃,have unique physical properties such as good thermal stability,in-plane anisotropy,bendability and high mobility.They are widely used in electronic and optoelectronic devices such as photodetectors and field effect transistors.In recent years,the research on Artificial Microstructure,optical microcavity,strain and heterojunction based on two-dimensional semiconductor materials has been greatly developed,which shows that two-dimensional semiconductor materials can have great development space in the field of Optoelectronics in the future through a series of research.In this thesis,the growth of two-dimensional semiconductor Sn S and Sn Se materials and the preparation of In Se and In₂Se₃materials are systematically studied.The application of strain,interface,optical engineering and heterojunction to improve their photoelectric properties is combined.The main contents are summarized as follows.(1)An improved version of physical vapor deposition is adopted Two dimensional Sn S,Sn S_0.5Se_0.5and Sn Se nanosheets were grown by physical vapor deposition method.It was found that after randomly adding S atoms into the snse crystal structure,the three representative components Sn S,Sn S_0.5Se_0.5and Sn Se were confirmed to have high crystal quality,Raman anisotropic behavior and adjustable photoelectric properties.In addition,we constructed the photoelectric structure of 2D on 3D mixed dimensional heterostructure Sn S_0.5Se_0.5/Ga As,and the detector shows superior self driving light detection performance,including high light response rate of 10.2 A/W and fast response of 0.5/3.47 ms.in addition,polarized light sensitive detection performance is obtained,and the dichroism ratio reaches1.25 and 1.45 at 405 nm and 635 nm,respectively.These impressive results show the potential of Sn S_0.5Se_0.5/Ga As heterostructure in multifunctional optoelectronic applications power.(2)"Suspension"is formed by etching SiO₂window?-In₂Se₃channel can effectively eliminate the influence of interface defects and scattering on the performance of devices based on traditional Si O₂.The theoretical and experimental results show that the suspension is effective local strain is induced in?-In₂Se₃,so as to adjust the energy band structure and introduce the intramolecular type II energy band arrangement,optimize the interfacial charge transfer and improve the photoelectric detection performance.Thus,the device shows excellent photosensitivity(the response is 1672 A/W,the switching ratio is 263,and the detection rate is 7.5×10¹³Jones),the response speed is relatively fast(12 ms for both rise and fall).The structure can also be extended to inse devices to comprehensively improve its optical detection performance to prove the wide applicability of the suspension method.(3)Build Photodetectors of?-In₂Se₃and In Se coupled with silicon nano optical array.On the one hand,silicon nano arrays provide Mie type resonance,which greatly improves the light absorption of two-dimensional materials.On the other hand,the introduction of photoconductive gain and strain engineering prolongs the lifetime of photogenerated carriers and accelerates their transmission.The common coupling effect of the three mechanisms of horizontal homojunction,vertical heterojunction and optical engineering greatly makes up for the weak optical absorption caused by the thin atomic thickness and short photogenerated carrier life,so that the device shows high optical detection performance.The constructed?-In₂Se₃device has high response of 9.4×10~3A/W and fast rise/decay time of 2.7/3.8 ms.These results show that advanced device design is an effective way to realize high-sensitivity multifunctional optoelectronic devices in the future.(4)The submillimeter tungsten selenide(WSe₂)prepared by two-way ventilation is used as substrate and passivation material to provide spatial uniformity and clean interface with low trap state.Based on the unique transport mechanism,the depletion region can be controlled by adjusting the gate voltage,so obtain high-performance In Se/WSe₂van der Waals heterostructures.Our research has certain guiding significance for the design and preparation of passivated substrates and heterostructures for high-performance photodetectors.(5)We have demonstrated a novel mixed-dimensional vd Wh photodetector consisting of In₂Se₃,h-BN and Cs Pb(Br/I)₃QDs.Such a device structure can encapsulate high-quality QDs,sequestering moisture and oxygen,which would greatly reduce their degradation.It is revealed that under illumination,the photoexcited electrons experience the charge transfer from QDs to In₂Se₃through quantum tunneling,while the photoinduced holes are confined in QDs,from which a high photoconductive gain is accomplished.The photodetector exhibits an external quantum efficiency exceeding 3.4×10~4%,a short rise time of 9.5 ms,and excellent on/off ratio of 2×10~6.Furthermore,Due to the efficient light absorber of perovskite QDs together,high-mobility of In₂Se₃,our 2D/0D vd WH can be further applied for weak light detection with high responsivity(3.9×10~3A/W)and superior detectivity(4.34×10¹⁴Jones)upon 405 nm light illumination.It is believed that the strategy using 2D/0D heterostructures to construct high-performance photodetectors warrant more research attention in the future.