Fig. 5: Emulation of the synaptic functions by the InSe artificial synaptic device. | Nature Communications

Fig. 5: Emulation of the synaptic functions by the InSe artificial synaptic device.

From: Oxidation-boosted charge trapping in ultra-sensitive van der Waals materials for artificial synaptic features

Fig. 5

a Schematic illustration of a biological synapse and the InSe artificial synaptic device. b EPSC generated by applying several input spikes with different voltage amplitudes under the potentiation condition of −80, −70, −60, −50, and −40 V, respectively. The drain voltage is set as 0.1 V under the Read operations. The change of PSC after the input spike (ΔPSC) is labelled by arrows. Inset shows the calculated w for the case of InSe A- (Brown) and V-FET (Turquoise) devices. c Variation of w under different pulse widths. d Extracted PPF index ((A2 − A1)/A1) versus spike time interval Δt, where A1 and A2 are the first and second EPSC peak, respectively. The solid line is the fitted curve based on the double exponential function. e The plot of IPSC changes over 120 s after stimulating by various numbers of the input pulse. The inset shows the corresponding changes after 1 and 50 pulses in InSe V-FET. f Monitored PSC under several sequential voltage pulses with various amplitudes (pulse width of 50 ms, time interval of 100 ms), which correspond to dynamic depression and potentiation behaviours in PSC. g Changes of synaptic weight (Δw) depending on the Time interval (ΔT) to emulate the STDP behaviour and the corresponding fitted curves based on the exponential functions. Note that the Δw is defined as (ΔPSC2 − ΔPSC1)/ΔPSC1, where ΔPSC1 and ΔPSC2 represent the obtained changes of PSC response after the pre- and postsynaptic simulations, respectively. The fitted lines are provided as a guide to the eye. The inset shows the schematic of the separated input signals from two terminals with the pulse width of 200 ms. h The potentiation and depression weight states of the conductance (G) extracted from InSe A-FET device under 100 successive input pulses. The inset shows the Gmax/Gmin (conductance margin) under 50 pulses (38.1) to 100 pulses (65.3), respectively. i The schematic of ANN-based on InSe A-FET devices for image recognition. j The obtained recognition rates as a function of training phases for 100 weight states.

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