Syntheses,Performance And Device Research Of Two-dimensional ?-In₂S₃

Two-dimensional(2D)layered materials such as graphene and transition metal sulfides(TMDs)have strong lateral chemical bonds in the plane,but the van der Waals interaction between the planes is very weak.In the past few decades,it has received great attention from scientific researchers.But in fact,most composite materials in nature have the non-layered characteristics of three-dimensional atom bonding.Inspired by the layered ultra-thin 2D crystals,it can be predicted that the numerous non-layered materials in the 2D structure can bring unique properties and advanced functions that cannot be achieved by their congeners.As an emerging 2D non-layered material,indium trisulfide(In₂S₃)is a typical IIIA-VIA non-layered semiconductor,which has huge application prospects in the field of electronic and optoelectronic devices.In this paper,physical vapor deposition(PVD)technology is used,with In₂S₃powder as the reaction source,fluorphlogopite flakes as the substrate,and based on van der Waal epitaxial growth technology;high-quality two-dimensional?-In₂S₃flakes and large areas with abundant crystals are prepared.The field effect transistors and memristive transistors based on the two-dimensional?-In₂S₃ continuous film are prepared,and the relevant performance tests of the devices are carried out.The results of the study are summarized as follows:1.Successfully prepared 2D?-In₂S₃ flakes with different thicknesses,and systematically studied the thickness-related photoluminescence,Raman spectra and transmittance spectra.Low-temperature photoluminescence and X-ray photoelectron spectroscopy were used to study the specific phenomenon that the peak of?-In₂S₃thinning to a few nanometers becomes a broad photoluminescence peak centered at520 nm.The temperature-independent photoluminescence peak position and stable O_1s level detected on the surface of the?-In₂S₃ sheet indicate the formation of In₂O₃on the surface of the sheet.In₂O₃ determines and affects the optical properties of the ultra-thin?-In₂S₃ sheet.These results can also explain the disappearance of the Raman characteristic peaks of the atomically thin?-In₂S₃ flakes and the huge difference in the visible light absorption coefficient of the ultra-thin and thick?-In₂S₃flakes.The tetragonal?-In₂S₃ sheet exhibits angle-dependent polarization Raman response under both parallel and crossed vertical polarization structures,which proves the strong in-plane optical anisotropy in the 2D?-In₂S₃ sheet,and strongly proves that2D?-In₂S₃.The crystal structure of the flakes is a tetragonal phase.The experimental and theoretical research in this article has deepened the understanding of the basic characteristics of 2D non-layered structure and provided enlightenment for the further research of 2D non-layered structure materials.2.We synthesized large-area 2D?-In₂S₃ continuous thin film by physical vapor deposition method,and used optical microscope,scanning electron microscope,Raman spectroscopy,X-ray diffraction,transmission electron microscope,atomic force microscope and photoluminescence spectroscopy.The morphology,thickness,crystal structure,and optical properties of the continuous?-In₂S₃ film were characterized.At room temperature,the traditional photolithography technology is used to fabricate field effect transistors based on two-dimensional In₂S₃ continuous thin films.The results show that 2D?-In₂S₃ continuous thin films are formed by 2D?-In₂S₃thin sheets that are laid on each other through large-area planar contact.The structure of 2D?-In₂S₃ film is tetragonal phase,with high crystalline quality.The current and voltage dependence of field effect transistors based on 2D?-In₂S₃ thin film confirms that 2D?-In₂S₃ thin film is a typical n-type semiconductor.The manufactured photodetector exhibits highly stable and reproducible light response characteristics.These results all indicate that 2D?-In₂S₃ continuous thin films have good application prospects and development in the field of electronics and optoelectronics in the future.3.A memristive transistor based on a two-dimensional non-layered?-In₂S₃ thin film metal chalcogenide material film was successfully fabricated.In₂S₃ grown by physical vapor deposition has microscopically visible grain boundaries(GBs)due to the stacking and interconnection of 2D In₂S₃ flakes to form a thin film.The memristive transistor based on the In₂S₃ film shows an adjustable bipolar resistance state with a resistance ratio of up to 10⁵.The high-low resistance state remains stable after endurance tests over 200 cycles,and the retention time is greater than 10⁴s.Irradiation from visible light and near-infrared light can induce an intermediate resistance state in the thin film transistor,thereby realizing light-modulated multilayer storage.In addition,memristive transistors can simulate synaptic functions with long-term potentiation(LTP)and long-term inhibition(LTD)by responding to pre-synaptic stimulation and adjusting the peak value of the gate pulse.More importantly,the plasticity of the synaptic behavior of LTP and LTD can be adjusted by simply changing the peak value of the gate voltage.In short,the multiple optoelectronic properties and controllable functions of thin-film memristive transistors based on the emerging 2D In₂S₃ provide a very meaningful guidance for the potential applications of electronic memory and artificial synapses.