Fig. 3: Working mechanism of the PPMS.
a Comparison of the transfer curves measured in the dark and under illumination. Red and blue dashed arrows indicate the threshold voltage shift (∆V) and switch ratio of sensor during electrical characterization. b Transfer curves measured in the sensor under the illumination of different effective laser power (from 0.0175 nW to 0.125 nW). c Extracted negative and positive threshold voltages (Vthn and Vthp) under different laser power. The ∆V approaches saturation under an optical power of ~0.035 nW, which is highlighted by the green dashed box. Current evolution triggered by positive and negative electrical pulses (d) without and (e) with illumination (P532 nm = 0.175 nW). f Current evolution triggered by polarity-dependent electrical pulses assisted under short-term illumination (P532 nm = 0.175 nW). The orange-shaded region represents the electro-optical co-modulation region, where electrical and optical stimuli collaboratively modulate the sensor response. The dynamic optical responses of the sensor are characterized when it is pre-configured to the (g) low-resistance state (state 1) and (h) high-resistance state (state 0) with the assistance of illumination (indicated by green shaded areas). The magnified views in Figures g and h exhibit characteristic photodetection responses, demonstrating that the sensor operates in perception mode under optical excitation.
