Gate Tuning of Synaptic Functions Based on Oxygen Vacancy Distribution Control in Four-Terminal TiO2−x Memristive Devices

Recent developments in artificial intelligence technology has facilitated advances in neuromorphic computing. Electrical elements mimicking the role of synapses are crucial building blocks for neuromorphic computers. Although various types of two-terminal memristive devices have emerged in the mains...

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Bibliographic Details
Published in:Scientific reports 2019-07, Vol.9 (1), p.1-7, Article 10013
Main Authors: Nagata, Zenya, Shimizu, Takuma, Isaka, Tsuyoshi, Tohei, Tetsuya, Ikarashi, Nobuyuki, Sakai, Akira
Format: Article
Language:English
Subjects:
639/301/1005/1007
639/301/1005/1008
Artificial intelligence
Computers
Conduction
Crystal structure
Electrodes
Gating
Humanities and Social Sciences
Microscopic analysis
Mimicry
multidisciplinary
Oxygen
Plasticity
Science
Science (multidisciplinary)
Spectrum analysis
Synapses
Synaptic plasticity
Titanium dioxide
Transmission electron microscopy
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Summary:Recent developments in artificial intelligence technology has facilitated advances in neuromorphic computing. Electrical elements mimicking the role of synapses are crucial building blocks for neuromorphic computers. Although various types of two-terminal memristive devices have emerged in the mainstream of synaptic devices, a hetero-synaptic artificial synapse, i.e ., one with modulatable plasticity induced by multiple connections of synapses, is intriguing. Here, a synaptic device with tunable synapse plasticity is presented that is based on a simple four-terminal rutile TiO 2−x single-crystal memristor. In this device, the oxygen vacancy distribution in TiO 2−x and the associated bulk carrier conduction can be used to control the resistance of the device. There are two diagonally arranged pairs of electrodes with distinct functions: one for the read/write operation, the other for the gating operation. This arrangement enables precise control of the oxygen vacancy distribution. Microscopic analysis of the Ti valence states in the device reveals the origin of resistance switching phenomena to be an electrically driven redistribution of oxygen vacancies with no changes in crystal structure. Tuning protocols for the write and the gate voltage applications enable high precision control of resistance, or synaptic plasticity, paving the way for the manipulation of learning efficiency through neuromorphic devices.
ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-019-46192-x