Mimic Drug Dosage Modulation for Neuroplasticity Based on Charge‐Trap Layered Electronics

Abstract

The human brain is often likened to an incredibly complex and intricate computer, rather than electrical devices, consisting of billions of neuronal cells connected by synapses. Different brain circuits are responsible for coordinating and performing specific functions. The reward pathway of the synaptic plasticity in the brain is strongly related to the features of both drug addiction and relief. In the current study, a synaptic device based on layered hafnium disulfide (HfS2) is developed for the first time, to emulate the behavioral mechanisms of drug dosage modulation for neuroplasticity. A strong gate‐dependent persistent photocurrent is observed, arising from the modulation of substrate‐trapping events. By controlling the polarity of gate voltage, the basic functions of biological synapses are realized under a range of light spiking conditions. Furthermore, under the control of detrapping/trapping events at the HfS2/SiO2 interface, positive/negative correlations of the An/A1 index, which significantly reflected the weight change of synaptic plasticity, are realized under the same stimulation conditions for the emulation of the drug‐related addition/relief behaviors in the brain. The findings provide a new advance for mimicking human brain plasticity.

Photonic synapses with ultralow energy consumption for artificial visual perception and brain storage

“…2(d) which is four orders of magnitude faster than the instantaneous information transmission in the biological synapses (typically 50 ms) 58 . Possible reasons for the ultrashort optical pulse detection capability are ultrafast optical signal propagation speed 2,35,39,59 and ultrasensitive optical detection 60 based on the polycrystalline MoS 2 films. As a result, our synaptic transistors could improve the recognition rate of single optical pulse significantly and achieve an ultralow power consumption of 40 aJ, two orders of magnitude lower than that of biological synapses.…”

“…Yoo's group 37 has confirmed that the MoS 2 layer could act as a high-efficiency charge-trapping layer via control experiment. Although the two-terminal devices are easier to form a crossbar-array structure, the inhibitory synaptic behaviours cannot be achieved in these devices 39 . Furthermore, three-terminal gate-control synaptic transistors are able to possess another degree-of-freedom to modulate the neuromorphic function apart from optical modulation 8,40 .…”

“…The proposed mechanism for photonic synapses is charge trapping/detrapping or phase change 5,39 . The former could achieve low-energy consumption instead of the requirement of high power supplies for the latter 39 .…”

“…The proposed mechanism for photonic synapses is charge trapping/detrapping or phase change 5,39 . The former could achieve low-energy consumption instead of the requirement of high power supplies for the latter 39 . In addition, the trap centers capturing and releasing carriers could be material defects, surface dangling bonds, potential wells 35 , etc 42 .…”

“…The persistent photocurrent/photoconductivity caused by these trap centers make the device be able to mimic some specific functions of biological synapses 26 . Given that, the TMDs with outstanding photoelectric conversion properties and various defects as carrier traps show great potential acting as optically active layers for photonic synapses 39 . Additionally, the von Neumann bottleneck caused by separated memory units and processing makes synaptic devices with low power consumption more desired 43 .…”