Resistive switching memory based on chitosan/polyvinylpyrrolidone blend as active layers

We report on resistive switching in ReRAM devices that use chitosan/PVP composite as the active layers. Al/chitosan+PVP/Ag and ITO/chitosan+PVP/Ag devices, each consisting of chitosan/PVP active layer having 1:3, 1:1 and 3:1 chitosan to PVP ratio were studied. Asymmetric threshold switching with V_th=−1.21 V and V_hold=−0.34 V only in the negative voltage bias was obtained for the Al/chitosan+PVP(1:3)/Ag device. The Al/chitosan+PVP(1:1)/Ag device showed better memory behaviour relatively. This device showed bipolar switching with V_SET=+0.75 V, and V_RESET=−0.28 V, then asymmetric TS with V_th=+0.84 V and V_hold=+0.19 V and lastly back to bipolar switching with V_SET=+0.77 V and V_RESET=−045 V, during the first, second and third voltage sweeping cycles. We attributed the switching in this device to the formation and rupture of conductive filaments due to Ag ions migration. On the other hand, the Al/chitosan+PVP(3:1)/Ag showed no memory behaviour. In comparison, all ITO/chitosan+PVP/Ag devices did not show any memory characteristics. This indicating the role of the Al/chitosan+PVP interface in the Al/chitosan+PVP/Ag system. Furthermore, we observed the possibility of compliance current dependent or sweeping cycle-dependent decrease in resistance and change from linear to exponential current behaviour in ITO/chitosan+PVP/Ag devices. Resistive switching based on chitosan/PVP blend is essential for biodegradable and environmentally friendly devices. Our results reveal the applicability of chitosan/PVP blend in memory device fabrication and that both the memory and switching can be exploited by varying the ratio of chitosan to PVP in the composite. Lastly, our results demonstrate the importance of electrode material in ReRAM devices.