Paper Title
DEMONSTRATION OF SYNAPTIC CHARACTERISTICS OF Ti/BaOx/n+-Si DEVICE

Abstract
Recently, there has been an increasing requirement for computing performance and efficiency. Traditional Von Neumann architecture, whose principle is to separate the central processing unit (CPU) and memory, not only limits the performance of the computer but also causes a large amount of energy consumption. Artificial synaptic device has been widely recognized as a solution to solve theVon Neumann bottleneck. Among semiconductor devices, resistive random-access memory device is considered suitable for realizing artificial synapses. In this study,a barium oxide (BaOx)synaptic device is proposed. The BaOxactive layer was deposited on a n+-Si substrate using a sol-gel process.Then, theBaOx/n+-Si sample was annealed at 500 °Cin vacuum for 30 min.The BaOx was cured and densified because of the high-temperature annealing.After that,a thermal evaporator with a shadow mask was used to deposit and patternTi metal on the BaOx active layer as top electrodes. Theartificial synaptic behavior of the Ti/BaOx/n+-Si device was evaluated using DC voltagesweeps and voltage pulses.Fig. 1 shows current-voltage characteristics of the Ti/BaOx/n+-Si device measured with a DC voltage cycle of 0 -6 V  0 6 V  0.When the first negative voltage sweep is applied to the Ti electrode, oxygenions in the BaOx layer are gradually repelled, resultingin generation ofoxygen vacancies.The conductance of theBaOx synaptic device gradually increases. Therefore, when the voltage sweeps backward from -6 V to 0, the device shows a higher conduction current. In contrast, when a positive voltage is applied to the Ti electrode, oxygen ions in the BaOx layer are attractedto fill the oxygen vacancies, leading to a decrease in oxygen vacancy content of the device. The conductance of the BaOx synaptic device gradually decreases. Hence, the device shows a lower current when the voltage sweeps back from 6 V to 0. The conductance modification of the BaOx device is dominated by oxygen vacancy content in the BaOxactive layer.Fig. 2 revealssynaptic characteristics of the BaOx device. The device conductance can gradually increase with increasing pulse number, demonstrating a synapticpotentiation behavior.Synaptic depression function can also be successfully obtained when successive positive voltage pulses are applied to the device.Satisfactory linearitiesin potentiation and depression characteristicsare observed.Moreover, paired pulse facilitation effect and spike-timing-dependent-plasticity (STDP) behavior can also be mimicked by the Ti/BaOx/n+-Si device.This study demonstrates synaptic functionsof the Ti/BaOx/n+-Si device.Artificial synapses are crucial to advancement of artificial intelligence and neuroscience. The proposed BaOxsynaptic device will contribute to the development of future neuromorphic computing systems. Keywords - Barium Oxide(BaO), Artificial Synapse, Neuromorphic Computing