Fig. 4: Electronic characteristics and optoelectronic properties of the ferroelectric CuVP2S6-based synapse.
a Schematic illustration of the ferroelectric graphene/CuVP2S6/graphene device. b Short-term potentiation effects triggered by electrical pulses of varying amplitudes (−1, −1.3, −1.5, −1.7 and −2 V, 10 ms) with 0.1 V bias for state reading. c Short-term potentiation effects stimulated by pulses of diverse widths (10, 20, 30, 40 and 50 V, 1.5 V), device states read at 0.1 V voltage. d PPD index plotted against pulse interval time, defined as (A2-A1)/A1 × 100%, with the red fitted curve via a double exponential function. Inset: PPD effect induced by voltage pulses with definitions of A1, A2, and time intervals Δt. e Excitatory PSC induced by a series of electrical pulses with frequencies of 10, 20, 25, and 50 Hz and device states read at 0.1 V bias, indicating more pronounced accumulation effects induced by higher pulse frequencies. f For LTP, 96 pulses are applied with a voltage range of 0.1 to 2.02 V for 10 ms, whereas for LTD, 118 pulses are used with a voltage range of −0.02 to −2.38 V for 10 ms, with state readout at 0.1 V bias. g PSC variations with different light pulse illumination times (0.1, 0.5, 1, 1.5, 2 and 2.5 s) are tested at 117 W cm⁻², read at 0.1 V. h PPF index plotted against pulse interval time, given by (A2 - A1)/A1 × 100%. The red curve fitted by a double exponential function. Inset: PPF effect induced by light pulses with definitions of A1, A2, and time intervals Δt. i Excitatory PSC versus time stimulated by N presynaptic spikes (N = 10, 20, and 30), with a pulse laser power density of 117 W cm−2, pulse width of 500 ms, read at 0.05 V.
