Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
, 2019, 1618798
eCollection

A Photoelectric-Stimulated MoS 2 Transistor for Neuromorphic Engineering

Affiliations

A Photoelectric-Stimulated MoS 2 Transistor for Neuromorphic Engineering

Shuiyuan Wang et al. Research (Wash D C).

Abstract

The von Neumann bottleneck has spawned the rapid expansion of neuromorphic engineering and brain-like networks. Synapses serve as bridges for information transmission and connection in the biological nervous system. The direct implementation of neural networks may depend on novel materials and devices that mimic natural neuronal and synaptic behavior. By exploiting the interfacial effects between MoS2 and AlOx, we demonstrate that an h-BN-encapsulated MoS2 artificial synapse transistor can mimic the basic synaptic behaviors, including EPSC, PPF, LTP, and LTD. Efficient optoelectronic spikes enable simulation of synaptic gain, frequency, and weight plasticity. The Pavlov classical conditioning experiment was successfully simulated by electrical tuning, showing associated learning behavior. In addition, h-BN encapsulation effectively improves the environmental time stability of our devices. Our h-BN-encapsulated MoS2 artificial synapse provides a new paradigm for hardware implementation of neuromorphic engineering.

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
The h-BN-encapsulated MoS2 synaptic transistor for neuromorphic engineering. (a) Schematic of h-BN-encapsulated MoS2 synaptic transistor. (b) Schematic diagram of biological neurons and synapses as a bridge of neuronal connections. (c) False-color SEM image of h-BN-encapsulated MoS2 synaptic transistor. (d) The Raman mapping of h-BN-encapsulated MoS2 synaptic transistor at 405 cm−1, where the black and gray dashed areas represent the h-BN/MoS2 overlap region and channel MoS2, respectively. (e) Raman shift of the MoS2 characteristic peak is 385,405 cm−1. (f) A significant peak was observed in the PL spectrum of MoS2 at 1.88 eV photon energy, which is consistent with the band gap of multilayer MoS2.
Figure 2
Figure 2
Characteristics of h-BN-encapsulated MoS2 synaptic transistor under electrical stimulation. (a) Transfer curve under different Vds. (b) Selecting the optimal base and pulse for the excitatory synapse by gain, when base of -3 V and pulse of -4 V, the maximum gain is obtained. (c) Selecting the optimal pulse of inhibitory synapse by gain and long-term synaptic weight change, the maximum inhibition effect and weight change are obtained when pulse is 8 V. (d) Frequency plasticity of inhibitory synapses, and the gain gradually decreases as the frequency increases. (e) Accumulation of postsynaptic current characteristics under 30 excitatory and inhibitory pulse stimulations. (f) Postsynaptic current characteristics as a function of progressive excitatory and inhibitory pulse stimulation numbers, showing long-term potentiation and inhibition effects.
Figure 3
Figure 3
Pavlov's dog classical conditioning experiment implemented by h-BN-encapsulated MoS2 synaptic transistor. Pavlov's dog classical conditioning experiments can be simulated on the proposed h-BN-encapsulated MoS2 synaptic transistor by efficient electrical modulation. Vbg (base, pulse) of (-5, -4 V) applied to the presynaptic gate is considered to be “bell” (NS), and Vbg (base, pulse) of (-3, -4 V) is considered “food” (US). The postsynaptic source drain channel current acts as synaptic weight, and the synaptic weight of 20 nA is defined as the threshold for the “salivation” response.
Figure 4
Figure 4
Basic synaptic characteristics of h-BN-encapsulated MoS2 transistor under optical stimulation. (a) Schematic diagram of h-BN-encapsulated MoS2 synaptic transistor under optical stimulus. (b) Single-laser pulse characteristics under different Vbg (0, -5, -10 V). (c) Variation of postsynaptic current amplitude under different Vbg (0, -5, -10 V) and single-laser pulses of different wavelengths (473, 532, 655 nm). (d) Typical paired laser pulse facilitation characteristics. (e) PPF characteristics as a function of paired laser pulse intervals. (f) Postsynaptic current characteristics are a function of excitatory laser pulses and inhibitory electrical pulse stimulation, which also shows long-term potentiation and depression.
Figure 5
Figure 5
Optical neural plasticity of h-BN-encapsulated MoS2 synaptic transistor. (a) Typical long-term potentiation of h-BN-encapsulated MoS2 synaptic transistor under optical stimulation. (b) Magnification of the dotted circle area in (a). (c) Gain variation of different wavelengths (473, 532, 655 nm) and pulse numbers under laser stimulation. (d) Long-term synaptic weight changes at different wavelengths (473, 532, 655 nm) and pulse numbers under laser stimulation. (e) Gain variation of different wavelengths and laser powers under optical modulation. (f) Gain as a function of laser wavelength and frequency in optical modulation mode.

Similar articles

See all similar articles

References

    1. Von Neumann J. First draft of a report on the EDVAC. IEEE Annals of the History of Computing. 1993;15(4):27–75. doi: 10.1109/85.238389. - DOI
    1. Backus J. Can programming be liberated from the von Neumann style? A functional style and its algebra of programs. Communications of the ACM. 2007;21(8):613–641. doi: 10.1145/359576.359579. - DOI
    1. Wright C. D., Hosseini P., Diosdado J. A. V. Beyond von-Neumann computing with nanoscale phase-change memory devices. Advanced Functional Materials. 2013;23(18):2248–2254. doi: 10.1002/adfm.201202383. - DOI
    1. Indiveri G., Liu S.-C. Memory and information processing in neuromorphic systems. Proceedings of the IEEE. 2015;103(8):1379–1397. doi: 10.1109/jproc.2015.2444094. - DOI
    1. Nawrocki R. A., Voyles R. M., Shaheen S. E. A mini review of neuromorphic architectures and implementations. IEEE Transactions on Electron Devices. 2016;63(10):3819–3829. doi: 10.1109/ted.2016.2598413. - DOI

LinkOut - more resources

Feedback