Figure 3. The performance of the optimized device and two examples for programming.

(a) Typical I–V curve of a single 1T1R cell for a quasi-DC sweep, the gate voltage is 1.8 and 8 V during SET and RESET process, respectively. Inset is a transmission electron microscope (TEM) image of the RRAM device. (b) An example of the typical continuous conductance tuning performance under an identical pulse train condition during SET process, along with the fitting curve. V_wl=2.4 V, V_bl=2.0 V (50 ns), V_sl=0 V. (c) Tuning performance during RESET operation, along with the fitting curve. V_wl=8 V, V_bl=0 V, V_sl=2.3 V (50 ns). (d) An example of the SET programming waveform applied on the first row to adjust the weight, following write-verify scheme. (e) Waveforms for programming without write-verify. (f) The precision measurement result during RESET process using verified pulse train with different amplitudes. y Axis represents the final conductance accuracy (the difference between the target conductance and the measured conductance over the target conductance) after programming from a same initial state 40 μS. (g) y Axis represents the number of pulses needed to reach the target conductance from the same initial state 40 μS. These curves show the relationship of tuning speed with respect to different programming pulse amplitudes.