Research Of Memelements In Metal Oxide/Graphene Composite Film

Nowadays,the development of computers is limited by the traditional von Neumann system,and the performance gap between memory and central processing unit will reduce the overall computing efficiency.The human brain with a unique architecture is considered to be the most effective tool for information processing.The basic functions of the biological brain,including perception,learning and memory functions,are achieved by a lot of neurons and synapses.The simulation of synaptic function is considered to be a key step in the realization of neuromorphic computing and artificial neural networks.In recent years,double-ended memelements have attracted more and more researchers'attention due to their simple device structure and high integration that can be used for synaptic simulation.However,there are still a lot of issues to be explored and solved to effectively improve the memelement storage characteristics and to realize functional applications of memelements,such as easy integration,low power consumption,fast operation,and response and recognition of external signals such as light and pressure,etc.Metal oxides are considered to be ideal materials for the development of high-performance memelements owing to their excellent optical,electrical and magnetic multifunctional properties,easy tunability of oxygen ion defect states,and compatibility with traditional complementary metal oxide semiconductors(CMOS).Two-dimensional materials(graphene)have some unique physical and chemical properties(such as ultra-high carrier mobility,adjustable band gap,high mechanical strength,etc.),which have been proved to have important application potential in the field of functional materials and devices.By compounding metal oxides with graphene-based nanomaterials with good electrical conductivity,such as reduced graphene oxide(rGO),high performance composite films with good mechanical and electrical conductivity can be constructed by modulating the interfacial interactions between them.At present,researchers have conducted researches on the application of iron-based oxides and graphene nanomaterials in memristors,but there are still many problems that need to be solved urgently,such as excessive operating voltage,poor resistance switching performance and storage capacity.In addition,iron oxide(Fe₂O₃)produces photo-response under light excitation,and the composite of graphene/metal oxide heterostructure also has a photoelectric effect.Therefore,it is worth studying to explore the possibility of the application of Fe₂O₃/graphene composite films in memelements and realize the functional application of devices.This thesis takes the Fe₂O₃/graphene composite films as the research point to explore its application in memelements.The main research contents and results are as follows:1.Preparation and characterization of rGO-Fe₂O₃thin films.We prepared graphene oxide(GO)/iron ion(Fe³⁺)composite ink,using GO as the template layer,filling Fe³⁺into GO nanosheet channel and then prepared different components of rGO-Fe₂O₃composite thin films.The relationship between structures and properties of rGO-Fe₂O₃thin films were investigated.2.Research on concurrent memristive and memcapacitive memelement based on rGO-Fe₂O₃thin film.To explore the possibility of the application of rGO-Fe₂O₃thin film as a memory material,memelement with a“sandwich”structure of Ag/rGO-Fe₂O₃/Si was designed and fabricated based on the charge trapping mechanism.The device has stable,smooth and gradual analog resistance behavior and obvious memcapacitive characteristics.In addition,the memory characteristics of the device were also studied The results show that the device has the benefits of low operating voltage,high switching ratio,long current and capacitance retention time,and can be used to simulate the potentiation and depression of synapses.The realization of concurrent memristive and memcapacitive memelement based on rGO-Fe₂O₃composite film provides a feasible solution for the application of memelement in multiple memory parameters.3.Research on photomemristor based on rGO-Fe₂O₃thin film.An external parameter-light was introduced to investigate the resistive behavior of rGO-Fe₂O₃films based on different components in the photomemristor in order to realize the functional application of the memelement.The device effectively enhances the photocurrent,switching ratio,and decreases the operating voltage of the photomemristor.Based on the conductive filament mechanism,the tuning of light makes the carrier transmission easy to be controllable and stable,realizing the detection,storage and processing functions of optical signals,enriching the functional applications of memristors,and reducing the energy consumption of the device.In summary,we prepared rGO-Fe₂O₃composite films using GO as a template and explored their application researches in concurrent memristive and memcapacitive memelement and photomemristor,realizing multi-storage parameters and functional applications.It provides an experimental basis for the future development trend of memelements(multi-storage parameters and functional applications).