Solution-Processed, Electrolyte-Gated In₂O₃ Flexible Synaptic Transistors for Brain-Inspired Neuromorphic Applications

Abstract

Emulating the essential synaptic behaviors using single synaptic transistor has attracted extensive attention for building the brain-inspired neuromorphic systems. However, few reports on synaptic transistors fabricated by solution processes have been reported. In this article, the indium oxide synaptic transistors based on polyimide substrates were fabricated by a nontoxic waterinducement method at a low temperature, and lithium perchlorate (LiClO 4 ) was dissolved in polyethylene oxide as the gate electrolyte. For water-inducement process, comparable electrical properties of the synaptic transistors can be achieved by prolonging the annealing time rather than high-temperature annealing with a relatively short time. The effect of the annealing time on the electrical performance of the electrolyte-gated transistors annealed at various temperatures was investigated. It is found that the electrolyte-gated-synaptic transistor on polyimide substrate annealed at 200 °C exhibits high electrical performance and good mechanical stability. Due to the ion migration relaxation dynamics in the polymer electrolyte, various important synaptic behaviors such as the excitatory postsynaptic current, paired-pulse facilitation, high-pass filtering characteristics, and long-term memory performance were successfully mimicked. The electrolyte-gated synaptic transistors based on solution-processed In 2 O 3 exhibit great potential in neuromorphological applications.

Nonvolatile Memory and Artificial Synaptic Characteristics in Thin‐Film Transistors with Atomic Layer Deposited HfOx Gate Insulator and ZnO Channel Layer

“…[ 4–10 ] Besides two‐terminal memristors, a variety of three‐terminal or four‐terminal artificial synapses, called synaptic transistors, have been investigated because the drain current changes by gate biasing corresponds to the synaptic weight modulation. [ 11–20 ] Thanks to multi‐terminal configuration, the synaptic transistors enable to update synaptic weight by gate biasing during performing signal processing by drain biasing. In addition, the wide range of drain current with respect to gate and drain voltages provides substantial change of synaptic weight for reliable training operation.…”

“…In addition, the wide range of drain current with respect to gate and drain voltages provides substantial change of synaptic weight for reliable training operation. Until now, proposed synaptic transistors have employed various operation schemes such as electrical charging of floating‐gate or interface states, [ 11,12 ] tunable polarizations in gate insulator, [ 13,14 ] exchange of protons between oxide‐semiconductor channel and gate insulator, [ 15,16 ] exchange of Li ions between lithium electrolyte gate insulator and oxide channel layer, [ 17,18 ] and oxygen ionic redistribution between oxygen‐deficient gate insulator and oxide‐semiconductor channel. [ 19,20 ]…”

Recent Progress on Emerging Transistor‐Based Neuromorphic Devices

“…Electrolyte film with abundant cations (such as H + and Li + ) is used as the electrolyte gate layer. [ 15–17,111 ] Such electrolyte gate has good electronic insulation characteristics, which is similar to the traditional high‐k materials, such as HfO 2 , ZrO 2 , and Al 2 O 3 . [ 112–114 ] In addition, the freely movable ions in the electrolyte can be directionally moved and concentrated under the induction of an electric field.…”

Recent Advances in Flexible Organic Synaptic Transistors

“…Thus, the use of PI substrates is possibly beneficial to improve the thermal stability of the organic devices in a high-temperature environment. [93][94][95] From a chemical point of view, the PEN has a similar structure to PET. However, it shows more temperature resistance and also has excellent mechanical properties.…”