triggered by applying a large bias, conductive filaments with highly oxygen deficient
Magnéli phases (WO 3 – x – δ ) are formed. The residual Schottky-barrier is located at
either the top or bottom interface, depending on the polarity of the forming voltage.
Thus, the devices exhibit nonvolatile rectification and partially nonvolatile bipolar
resistive switching with configurable polarity, as shown in the upper and lower
illustrations in Fig. 16. In these cases, the device can be used as a diode, a resistor, a
switching element, and an artificial synapse with learning functions in long-term
dynamics.
4 Summary
In this chapter, we described the synaptic plasticity realized by various atomic switch
structures. Gap-type and gapless-type atomic switches using metal cations can
mimic the key features of the learning and memorization abilities in the human
brain, such as SM, STM, and LTM modes in the psychological multistore model.
The synaptic plasticity underlying these modes can be controlled by input voltage
pulse stimulations, which is similar to what occurs with biological synapses.
Depending on the matrix electrolyte material, sensitivity to the moisture in and
temperature of the ambient environment was also demonstrated, which suggests
the possibility of achieving advanced artificial synaptic elements with the ability to
sense environmental conditions. This result is a step toward mimicking the uniqueness of the human brain in its ability to perceive the environment. We also demonstrate an on-demand multiple electrical and neuromorphic functions using oxygen
anion migration in a WO 3 – x thin film. Configurable multifunction, including
volatile and nonvolatile resistive switching, rectification and synaptic plasticity in
both short-term and long-term dynamics, were attained. It should be emphasized that
all the functions described herein can be achieved in a single device, without the
need of external programming, which is difficult to achieve by on/off bi-stable
switching devices based on conventional CMOS transistors. Thus, our devices,
based on atomic switch technology, have great potential for use as essential components for configurable circuits, analog memories, and digital-neural fused network
systems.
References
1. Arnesano, F.: The role of copper ion and the ubiquitin system in neurodegenerative disorders.
In: Pignataro, B. (ed) Ideas in Chemistry and Molecular Sciences: Where Chemistry Meets Life.
WILEY-VCH, Weinheim (2010)
2. Ohno, T., Hasegawa, T., Tsuruoka, T., Terabe, K., Gimzewski, J.K., Aono, M.: Short-term
plasticity and long-term potentiation mimicked in single inorganic synapses. Nat. Mater. 10,
591 (2011)
Artificial Synapses Realized by Atomic Switch Technology
197
Magnéli phases (WO 3 – x – δ ) are formed. The residual Schottky-barrier is located at
either the top or bottom interface, depending on the polarity of the forming voltage.
Thus, the devices exhibit nonvolatile rectification and partially nonvolatile bipolar
resistive switching with configurable polarity, as shown in the upper and lower
illustrations in Fig. 16. In these cases, the device can be used as a diode, a resistor, a
switching element, and an artificial synapse with learning functions in long-term
dynamics.
4 Summary
In this chapter, we described the synaptic plasticity realized by various atomic switch
structures. Gap-type and gapless-type atomic switches using metal cations can
mimic the key features of the learning and memorization abilities in the human
brain, such as SM, STM, and LTM modes in the psychological multistore model.
The synaptic plasticity underlying these modes can be controlled by input voltage
pulse stimulations, which is similar to what occurs with biological synapses.
Depending on the matrix electrolyte material, sensitivity to the moisture in and
temperature of the ambient environment was also demonstrated, which suggests
the possibility of achieving advanced artificial synaptic elements with the ability to
sense environmental conditions. This result is a step toward mimicking the uniqueness of the human brain in its ability to perceive the environment. We also demonstrate an on-demand multiple electrical and neuromorphic functions using oxygen
anion migration in a WO 3 – x thin film. Configurable multifunction, including
volatile and nonvolatile resistive switching, rectification and synaptic plasticity in
both short-term and long-term dynamics, were attained. It should be emphasized that
all the functions described herein can be achieved in a single device, without the
need of external programming, which is difficult to achieve by on/off bi-stable
switching devices based on conventional CMOS transistors. Thus, our devices,
based on atomic switch technology, have great potential for use as essential components for configurable circuits, analog memories, and digital-neural fused network
systems.
References
1. Arnesano, F.: The role of copper ion and the ubiquitin system in neurodegenerative disorders.
In: Pignataro, B. (ed) Ideas in Chemistry and Molecular Sciences: Where Chemistry Meets Life.
WILEY-VCH, Weinheim (2010)
2. Ohno, T., Hasegawa, T., Tsuruoka, T., Terabe, K., Gimzewski, J.K., Aono, M.: Short-term
plasticity and long-term potentiation mimicked in single inorganic synapses. Nat. Mater. 10,
591 (2011)
Artificial Synapses Realized by Atomic Switch Technology
197