Ferroelectric-like charge trapping thin-film transistors and their evaluation as memories and synaptic devices

Daus, Alwin, Lenarczyk, Pawel, Petti, Luisa, Münzenrieder, Niko, Knobelspies, Stefan, Cantarella, Giuseppe, Vogt, Christian, Salvatore, Giovanni A, Luisier, Mathieu and Tröster, Gerhard (2017) Ferroelectric-like charge trapping thin-film transistors and their evaluation as memories and synaptic devices. Advanced Electronic Materials, 3 (12). p. 1700309. ISSN 2199-160X

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Abstract

This work presents a defect charging mechanism in 5-nm-thick amorphous Al2O3 thin-films fabricated on plastic, which leads to multistate memory effects, and thus the realization of synaptic thin-film transistors (TFTs) for neuromorphic applications. First, the Al2O3 thin-films are characterized in metal–insulator–metal stacks. These devices exhibit ferroelectric-like behavior, which is visible in the small-signal capacitance and the surface charge density. Furthermore, the quantum-mechanical simulation of the current–voltage characteristic leads to a physical model with trap charges close to the anode interface where deep-level traps are identified by fitting the experimentally obtained resonant tunneling peaks. The trap charge lifetime and frequency behavior is evaluated in InGaZnO4 TFTs, where the 5-nm-thick Al2O3 layer is employed as gate dielectric. At an operating voltage as low as ±2 V, a charge trapping retention up to ≈3 h and a discernable ON/OFF read-out with a factor >3 at 2 kHz are achieved. When subjected to a train of gate–source voltage pulses, the TFTs show charge integration properties which emulate facilitating and depressing behaviors of biological synapses. These results indicate that thin low-temperature defect-rich metal-oxide dielectrics may be candidates for low-voltage memory applications and neuromorphic circuits on unconventional substrates.

Item Type: Article
Schools and Departments: School of Engineering and Informatics > Engineering and Design
Research Centres and Groups: Sensor Technology Research Centre
Depositing User: Niko Munzenrieder
Date Deposited: 13 Dec 2017 12:01
Last Modified: 20 Dec 2017 10:43
URI: http://sro.sussex.ac.uk/id/eprint/72031

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