Impact of Top Electrodes (Cu, Ag, and Al) on Resistive Switching behaviour of Cu-rich Cu2ZnSnS4 (CZTS) Ideal Kesterite.

Abstract

Cu2ZnSnS4 (CZTS) active material-based resistive random-access memory (RRAM) devices are investigated to understand the impact of three different Cu, Ag, and Al top electrodes. The dual resistance switching (RS) behaviour of spin coated CZTS on ITO /Glass is investigated up to 102 cycles. The stability for all the devices (Cu/CZTS/ITO, Ag/CZTS/ITO, and Al/CZTS/ITO) is investigated up to 103 s in low- (LRS) and high- (HRS) resistance states at 0.2 V read voltage. The endurance up to 102 cycles with 30 ms switching width is showing the stable write and erase current. Weibull cumulative distribution plots suggest that Ag top electrode is relatively more stable for set and reset state with 33.61 and 25.02 shape factors, respectively. The charge carrier transportation is explained by double logarithmic plots, Schottky emission plots, and band diagrams, substantiating that at lower applied electric field intrinsic copper ions dominate in Cu/CZTS/ITO, whereas, at higher electric filed, top electrodes (Cu and Ag) dominate over intrinsic copper ions. Intrinsic Cu+ in CZTS plays a decisive role in resistive switching with Al electrode. Further the impedance spectroscopy measurements suggest that Cu+ and Ag+ diffusion is the main source for the resistive switching with Cu, and Ag electrodes.