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• INVESTIGATION OF SYNAPTIC PLASTICITY IN MEMRISTIVE CROSS-POINT STRUCTURES FOR NEUROMORPHIC ROBOTIC SYSTEMS

  R.V. Tominov , Z. Е. Vakulov , V.I. Varganov , I.О. Ignatieva , V. А. Smirnov

  200-207

  2025-12-30

  Abstract ▼

  The results show multilevel resistive switching and synaptic plasticity of a memristive cross-point based on a nanocrystalline zinc oxide film. It is shown that with a decrease in the amplitude and duration of input pulses, the memristive cross-point demonstrates resistive states from 4.27 × 10⁵ Ohm to 8.34 × 10⁷ Ohm. It is shown that the switching energy of some synaptic levels is picojoules, which is promising for creating compact low-power neuromorphic systems. Thus, it is shown that nanocrystalline ZnO films have synaptic plasticity, i.e. When applying voltage pulses, large limits and duration can vary depending on the synaptic levels.
  The fabricated memristive cross-point demonstrates paired-pulse facilitation PPF at t_p from 1 ms to 10 ms and pair-pulse depression PPD at t_p from 50 ms to 100 ms. The analysis of the experimental results of the PPF and PPD study showed that an increase in the number of pulses from 10 to 90 leads to an increase in postsynaptic current EPSC from 32 μA to 73 μA for t_p = 1 ms, from 31 μA to 59 μA for t_p = 5 ms, from 31 μA to 48 μA for
  t_p = 10 ms, and a decrease in EPSC from 30 μA to 25 μA for t_p = 50 ms, from 30 μA to 17 μA for t_p = 70 ms, from 30 μA to 5 μA for t_p = 100 ms. From the obtained results it follows that the interval between pulses, the higher the PPF index, thus it can be concluded that the manufactured memristive cross-point based on ZnO nanocrystalline films imitates the crucial plasticity of the biological synapse, in which the plasticity of PPF and PPD is determined by the concentration of Ca+ ions and which plays a role in many biological functions of the brain, such as determining the key source of sound, pattern recognition, associative learning, filtering unnecessary. information. The obtained results can be used for hardware implementation of neural networks, neuromorphic structures of robotic complexes, prostheses and artificial intelligence systems

• FORMATION AND INVESTIGATION OF DOPED ZINC OXIDE MEMRISTIVE FILMS FOR MACHINE VISION SYSTEMS OF ROBOTIC COMPLEXES

  Z. Е. Vakulov , R.V. Tominov , Д.A. Dzyuba , V.А. Smirnov

  116-123

  2025-11-10

  Abstract ▼

  The results of investigation of the influence of synthesis modes of doped zinc oxide thin films by pulsed laser deposition on their morphological and electrophysical characteristics are presented. Experimental studies of the influence of dimensional effects on the parameters of resistive switching of memristor structures based on thin films of doped zinc oxide have been carried out. The relationship between the morphological parameters of the films, their thickness and resistive switching characteristics has been established. The results showing how thickness, surface roughness and average grain diameter influence the ratio of resistance in the high-resistance and low-resistance states, as well as the switching voltages U_set and U_res have been obtained. It is shown that an increase in the thickness of gallium-doped zinc oxide films leads to an increase in the Uset and Ures voltages, while the dependence of the resistance ratio in the high-resistance and low-resistance states has a complex character, with a maximum observed at a film thickness of about 30 nm. The obtained results allow us to estimate the degree of influence of structural and morphological parameters of doped zinc oxide films on the resistive switching effect in them, and also to formulate recommendations for obtaining these films with the required resistive switching parameters. It was found that increasing the thickness of gallium-doped zinc oxide films from 11.8±5.1 nm to 55.1±18.4 nm it is possible to change the value of charge carriers concentration from (2.84±0.22)∙1019 cm-3 to (1.42±0.13)∙10²⁰ cm^-3, as well as the mobility of charge carriers from 54.48±4.07 cm²/(V∙s) to 18.77±0.83 cm²/(V∙s). At the same time, increasing the thickness of gallium-doped zinc oxide films also leads to an increase in resistance in the high-resistance state from 1.38±0.11 MΩ to 62.59±5.4 MΩ and resistance in the low-resistance state from 0.005±0.001 MΩ to 0.041±0.002 MΩ. The results obtained can be used in the development of physical principles of creation of electronic component base of artificial intelligence systems for manufacturing new devices and devices of nanoelectronics and adaptive neuromorphic systems