Sol-Gel Composites-Based Flexible and Transparent Amorphous Indium Gallium Zinc Oxide Thin-Film Synaptic Transistors for Wearable Intelligent Electronics

Jin-Gi Min,Won-Ju Cho

doi:10.3390/molecules26237233

Abstract

In this study, we propose the fabrication of sol-gel composite-based flexible and transparent synaptic transistors on polyimide (PI) substrates. Because a low thermal budget process is essential for the implementation of high-performance synaptic transistors on flexible PI substrates, microwave annealing (MWA) as a heat treatment process suitable for thermally vulnerable substrates was employed and compared to conventional thermal annealing (CTA). In addition, a solution-processed wide-bandgap amorphous In-Ga-Zn (2:1:1) oxide (a-IGZO) channel, an organic polymer chitosan electrolyte-based electric double layer (EDL), and a high-k Ta2O5 thin-film dielectric layer were applied to achieve high flexibility and transparency. The essential synaptic plasticity of the flexible and transparent synaptic transistors fabricated with the MWA process was demonstrated by single spike, paired-pulse facilitation, multi-spike facilitation excitatory post-synaptic current (EPSC), and three-cycle evaluation of potentiation and depression behaviors. Furthermore, we verified the mechanical robustness of the fabricated device through repeated bending tests and demonstrated that the electrical properties were stably maintained. As a result, the proposed sol-gel composite-based synaptic transistors are expected to serve as transparent and flexible intelligent electronic devices capable of stable neural operation.

Highlights

The von Neumann architecture poses significant challenges in the post-Moore era, processing large amounts of data and diverse information while providing ever-increasing computing power with low energy consumption [1,2,3]
The rapid advancement of display technology has accelerated the popularization of transparent and flexible electronic devices, which are expected to fulfill future technological requirements that are difficult to achieve with silicon-based electronic devices [16]
Considerable research has been conducted on flexible substrate materials such as polymer plastics, ultra-thin glass (UTG), and metal foil [16,19,20,21,22,23]

Summary

Introduction

The von Neumann architecture poses significant challenges in the post-Moore era, processing large amounts of data and diverse information while providing ever-increasing computing power with low energy consumption [1,2,3]. High gate capacitance (>1.0 F/cm2) can be achieved from high-density mobile protons owing to the EDL effect of proton-conductive chitosan electrolytes that allow synaptic behavior [11,12]. Polyimide (PI) is a widely used material owing to its low cost, excellent mechanical/chemical properties, and compatibility at high process temperatures [24,25,26,27,28].

Results

Conclusion