All-metal oxide synaptic transistor with modulatable plasticity

Abstract

The artificial neural system has attracted tremendous attention in the field of artificial intelligence due to operate mode of parallel computation which is superior to traditional Von Neumann computers in processing complex sensory data and real-time situations with extremely low power dissipation. Remarkable progress has been made in the hardware-based electric-doublelayer synaptic transistors as its modulation by ion movement is similar to biological synapse for the past few years. Unfortunately, long-term potentiation (LTP) timescale is still a big challenge in hardware-based electric-double-layer synaptic transistors which is essential to processing capacity and memory formation. Meanwhile, the effect of ion concentration on the synaptic plasticity has rarely been reported. Here, a solid state electrolyte-gated transistor using Ta 2 O 5 as dielectric layer with unique ionic composition was demonstrated and the regulation of synaptic weight was realized by changing ion concentration. Both the potentiation and depression of synaptic weight such as excitatory post-synaptic current, inhibitory response (IPSC), paired pulse facilitation as well as LTP were successfully simulated. More importantly, oxygen vacancy content was tuned for the first time to modulate synaptic plasticity by varying film thickness and gas ratio, through which the intensity and duration of memory were enhanced with appropriate vacancy concentration. It indicated that appropriate vacancy concentration avoided the effects of internal electric field induced by ion excess, leading to a long-term memory. These results reveal a promising path to improve memory capacity of artificial synapse via ion modulation.

Artificial Indium‐Tin‐Oxide Synaptic Transistor by Inkjet Printing Using Solution‐Processed ZrOx Gate Dielectric

“…This counter‐clockwise behavior can be explained by the EDL mechanism. [ 27 ] In addition, for the higher annealing temperature of ZrO x , the oxygen content increases and thus decrease in oxygen vacancies, which accorded well with the transfer curve drift (positive V TH shift) and the ON current drop in ITO TFT. Many groups reported the synaptic TFT using ionic gel electrolyte material as a gate dielectric.…”

“…[ 26 ] To make fully solution‐processed synaptic transistor is still challenging. The high‐k material such as AlO x , [ 26 ] TaO x , [ 27,28 ] HfO x , [ 29,30 ] and GdO x [ 25 ] are studied as a candidate for the gate dielectric of synaptic transistor.…”

Ultralow‐Power Synaptic Transistors Based on Ta2O5/Al2O3 Bilayer Dielectric for Algebraic Arithmetic

“…Consequently, the chemical signal is converted back to the electrical signal and finally induces EPSC or IPSC. [ 18 ] The proposed synaptic transistors can produce artificial EPSC/IPSC and achieve a variety of synaptic plasticity. Figure 1b is the structure of the Ta 2 O 5 /Al 2 O 3 bilayer gate‐dielectric synaptic transistors.…”

“…[ 13 ] Instead, three‐terminal synaptic devices, synaptic transistors, are more suitable for complex nerve networks and real‐time processing because of their additional gate terminal for synaptic weight update. [ 18 ] When a voltage spike is applied to the gate electrode, the channel conductance is modulated and read out synchronously by the drain bias voltage. Moreover, learning and memory functions can occur simultaneously in synaptic transistors.…”

Mixed‐Dimensional Van der Waals Heterostructures Enabled Optoelectronic Synaptic Devices for Neuromorphic Applications

“…effectively modulated, resulting in tunable plasticity such as the conversion between STP and LTP. [153,154] Because the chemical composition is always pre-defined during the material synthesis, it is expected to realize different plasticity in different devices rather than a single device. To obtain better adjustable plasticity modulation, an independent gate is used to control the conductance change of the device under the pre-synaptic stimuli by changing the polarity of bottom-gate voltages, which could result in the conversion between synaptic potentiation and depression.…”