Tds 2012b

A reference capacitor C_ref = 10 nF (Digi-Key, 399-12395-ND) is placed in series of the plasma cell. The applied voltage U_ext and the reference capacitor voltage drop U_ref are monitored using two high voltage probes (Tektronix, P6015A) with a digital oscilloscope (Tektronix, TDS 2012B). The surface charge on the ferroelectric electrode is equal to that on the reference capacitor which was obtained by its capacitance times its voltage drop. The total current through the plasma and the unavoidable parallel parasitic components is monitored with the current monitor (Pearson 6585). The equivalent circuit of the system is shown in Fig. 6a.Fig. 6

a Equivalent circuit of the electrical measurement. b Electric field-induced second harmonic generation (i.e., EFISH) for electric field measurement. L₁: plano-convex lens with a focal length of 400 mm; F₁: longpass filter with a cut-on wavelength of 650 nm; P: dispersive prism; L₂: collimating lens with a focal length of 750 mm; M: dichroic mirror that transmits 800 nm and reflects 400 nm; F₂: bandpass filter with a bandwidth of 10 nm centered at 400 nm.

Memristive properties were measured using a self‐built test system comprising a sourcemeter (2636A, Keithley), arbitrary function generator (3390, Keithley), oscilloscope (TDS 2012B, Tektronix), and probe station (TTPX, Lake Shore). A bias voltage was applied on the W top electrode and W bottom electrode was grounded. The positive direction of the bias voltage was defined such that the current flowed from the top to the bottom electrode. To measure the EPSC, the memristor was connected with a load resistor R_load of 1 MΩ in series, and the voltage drop across the R_load was monitored by an oscilloscope. Then, the monitored voltage was converted to the current flowing through the memristor. To implement pair‐ or triplet‐STDP, each pre‐ or postsynaptic spike applied to the top or bottom electrode was composed of a single spike with amplitude V+/V− = 1 V/−1 V and a width of 50 ms. The initial and final conductance states of the device (G₀ and G_final) were readout using a small pulse (0.1 V, 50 ms) before and after applying the programmable pulses, and the conductance change was defined as ΔG = G_final − G₀. Both the writing and reading of the memristor were performed in pulse mode.

The V_oc and I_sc values of preprocessing data were recorded in excel form using digital storage oscilloscope (Tektronix TDS2012B), semiconductor parameter analyzer (4200‐SCS), and current preamplifier (ITHACO, 1211) instruments. The originlab software was used to plat all the graphs and Figures S6 and S9 in the Supporting Information denoted the average output voltage value lines were calculated through microsoft excel. Finally, all displayed figures were allegiantly drawn by adobe illustrator.