Optoelectronic Hybrid Neuromorphic Multi-gate Transistors Based On MoS₂

The conventional computers using von Neumann structures will face a serious challenge as Moore’s Law approaches its end.The mainstream technology of scale reduction of integrated circuit（IC）has been developing towards the trend of technology endogenous power and application pull.In this context,inspired by the human brain,the construction of hardware-based neuromorphic computing system has become a research hotspot in recent years.In this article,the biopolymer polyvinyl alcohol（PVA）was used as the gate dielectric to prepare the MoS₂-based field effect transistor（FET）.Based on the photoelectric characteristics of MoS₂,the simulations of basic synaptic behaviors and some bionic functions were realized.The following researches were specifically carried out:（1）Preparation and characterization of PVA electrolyte film and MoS₂-based FET.The preparation of PVA gate dielectric was to mix polyvinyl alcohol powder and deionized water in a mass ratio of 1:9,stirring and dissolving at 70℃.MoS₂ thin slices with fewer layers were obtained by mechanical stripping method.The MoS₂-based FETs were fabricated by ultra-violet photoengraving electrodes and thermal vaporizer deposition of metals.This kind of biopolymer gate dielectric had good film forming property,stable performance,and conformed to the green sustainable development concept.The modification of PVA gate dielectric on MoS₂ surface can greatly improve the regulation ability of gate voltage on MoS₂ and produce some interesting physical phenomena,which was very important for the simulation of synaptic behaviors.（2）The basic photoelectric characteristics of MoS₂-based FET without biopolymer PVA gate dielectric were studied.The transfer characteristic curve of the device changed significantly with the change of the light intensity.The photoelectric characteristics of side-gate MoS₂-based FET with biopolymer PVA gate dielectric were studied.The operating voltage of the MoS₂ device was reduced from 20 V to 2 V.The device had a current switching ratio of about 10⁴ and carrier mobility of51 cm²·V^-1·s^-1.Obvious electrical and optical hysteresis phenomena were observed in the transfer curves of this device.（3）The bionic simulation of the neuromorphic optoelectronic device based on two-dimensional MoS₂ was studied.Some typical synaptic behaviors such as excitatory/inhibitory postsynaptic current（EPSC/IPSC）,paired-pulse facilitation（PPF）and dynamic filtering had been successfully simulated.Most importantly,different spike timing-dependent plasticity（STDP）learning rules were simulated under the regulation of bottom gate and Pavlov associative learning rules were simulated under the regulation of the coplanar side gate of the MoS₂-based FET.Finally,the learning rules of electrical STDP at different orientations were simulated by the multi-gate electric-double-layer transistor.In this article,the biomimetic characteristics of neuromorphology before and after using PVA as the gate dielectric were studied by a novel neuromorphic device of a MoS₂-based FET,which would make an exploration for the future construction of hardware-based neuromorphic system.