Amorphous Indium Gallium Zinc Oxide Based Electric-double-layer TFTs For Neuromorphic Bionic Applications

With the advent of the era of big data,information is showing an explosive growth trend.In the von Neumann architecture of traditional computers,the computing unit and storage unit are separated.Data interaction between the two requires a lot of energy consumption,which is not conducive to computing efficiency.Inspired by the human brain,neuromorphic electronics was proposed to effectively solve the above problems.Neuromorphic electronics aims to build brain-like computers to emulate the powerful information processing functions of the human brain.A brain-like computer integrates a computing unit and a storage unit,and is more efficient and energy-saving than traditional computers.The key step in building a brain-like computer is to start from the bottom layer to prepare synaptic devices with synaptic functions.Common synaptic devices are: phase change memory,atomic switch memory,memristor,floating gate transistor,ferroelectric transistor,and electric-double-layer transistor.Among them,the electric-double-layer transistor is the synaptic device that is more suitable for neuromorphic function emulation.The electric-double-layer transistor uses materials with electronic insulation and ion conductivity as the gate dielectric,which can form a stable electric double layer at the gate/gate dielectric and gate dielectric/semiconductor channel interface during operation,because the thickness of the electric double layer is only at the nanometer level,the gate dielectric can have a huge capacitance per unit area,and the transistor can work at a lower voltage to meet the needs of low power consumption.In addition,because the channel conductance of such transistor is regulated by the gate voltage,the process is similar to that of the neurotransmitter in the synapse for information transmission.The electric-double-layer transistor has a broader application prospect in the direction of neuromorphic functional bionics.The oxide thin film transistor represented by amorphous indium gallium zinc oxide(a-IGZO)has been widely studied due to its advantages such as higher electron mobility,large switching ratio,and low-temperature preparation,making it widely used in flat panel displays,transparent electronics,and The neuromorphic system and other fields have potential applications.Today,IGZO-based thin film transistors have broad application prospects in liquid crystal displays,organic light-emitting diode displays and other directions.In addition,IGZO-based thin film transistors also have advantages such as thin thickness,light weight,and flexibility,which make them have application potential in the field of flexible electronics.Based on amorphous indium gallium zinc oxide electric-double-layer transistors,this paper mainly conducts the following research:(1)Chitosan is a renewable natural resource that has been commercially produced.When it is dissolved in a dilute acid solution,it forms a positively charged electrolyte solution with good proton conductivity.The author selects chitosan as the gate dielectric and a-IGZO as the channel material to fabricate a rigid IGZO electric-double-layer thin film transistor.The device has a bottom gate structure.The function of an inverter is realized by connecting resistors in series on the device.(2)By adjusting the oxygen content during the sputtering of the IGZO film,the IGZO/Ag contact is modulated from an ohmic contact to schottky contact,and the schottky barrier is adjusted by controlling the number of scans of the gate voltage.Subsequently,the influence of the ratio of oxygen to the device performance was discussed.(3)A flexible IGZO electric-double-layer thin film transistor was fabricated on the PET substrate.The device has a bottom gate and planar multi-side gate structure.The author tested the mechanical properties of the flexible device and found that the electrical properties and gate dielectric capacitance of the flexible device changed little before and after bending,which proved that the prepared device has better mechanical stability.Finally,the device was used to emulate neuromorphic related functions.These functions mainly include: EPSC/IPSC,PPF,high-pass filtering,synaptic plasticity,and neuron processing of spatiotemporal information.The above results show that the electric-double-layer thin film transistors can operate at voltages as low as 2 V.The inverter function can be realized by adding resistance to the transistor,which can be used in logic circuit.Such transistors have good mechanical stability and application value in flexible electronics.The bionic function of transistors for neuromorphic computation has made the relevant foreshadowing.