Resistive Switching Of Light-controlled ZnO-memristive Synapses And The Emulation Of Neural Functions

In recent years,with the end of Moore?s law in sight,new computing architectures,like brain-like computation,are urgently needed to satisfy the increasing demands for big data processing.Memristors as synaptic electronic devices have important applications in brain-like computing.Neuromorphic architectures with photoelectric learning capability are good candidates for energy efficient computing for recognition and classification tasks.The research works of this thesis are:artificial synapses based on the ZnO_1-x/AlO_y heterojunction were fabricated and the photoelectric plasticity was investigated.Versatile synaptic functions were emulated based on the inherent persistent photoconductivity and volatile resistive switching characteristics of the device.A wide range from completely volatile to semi-volatile to non-volatile was achieved.Three-terminal memristor with low-power and high-efficiency was explored.The main research contents are as follows:ZnO has good photoelectric properties.The ITO/ZnO_1-x/AlO_y/Al memristor was fabricated by magnetron sputtering.Studies have shown that the memristor has obvious photoresponse to 310 nm UV light and PPC effect.The high resistance state was volatile after applied negative bias.Versatile synaptic functions such as photoelectric short-term/long-term plasticity,paired-pulse facilitation,neuromorphic facilitation and depression were emulated based on the inherent persistent photoconductivity and volatile resistive switching characteristics of the device.Under different compliance currents,Al/ZnO/Pd/Ti/SiO₂/Si devices were possible to obtain a wide range of continuously adjustable resistive switching from completely volatile to semi-volatile to non-volatile.The state of resistance can be continuously controlled by changing the positive and negative electrical pulse amplitudes.Three-terminal memristors were fabricated by trying different parameters such as the shape of the source and drain electrodes,the aspect ratio of the channel layer,and the materials and thickness of the barrier layer.The operating voltage and leakage current were reduced successful by the use of double-conducting ionic liquids.The device was found to have a 1000-fold optical response and pronounced PPC effect.We systematically studies the resistive switching and optoelectronic performance,and versatile synaptic functions were emulated based on the characteristics of the device.It is of great significance to the hardware development of neuromorphic functions with photoelectric learning ability.