Resistive switching behaviour in oxide thin films and devices

Abstract

Resistive switching effect induced by voltage pulses has been praised as one of the potential candidates for the next-generation non-volatile memories. Resistive random access memory (RRAM) based on transition-metal perovskite oxides has demonstrated a large resistance change upon the application of small and short voltage pulses with different polarities. Some of the advantages of the effect include its fast response, low power consumption, high information packing density and non-volatile characteristics. However, the resistive switching mechanism is still under debate, and the devices have to be optimized before they can be used commercially. The objective of this work is to study the properties of resistive switching effect based on perovskite manganites including Pr0.7Ca0.3MnO3 (PCMO) and La0.7Sr0.3MnO3 (LSMO), and to investigate the resistive switching mechanism. The research work includes the fabrication and subsequent characterization of PCMO and LSMO oxide thin film-based devices. The performance of the switching devices, including pulse magnitude and pulse width dependences of resistance ratio, data retention ability, and their durability towards repeated switching, have been studied. Moreover, the dependence of the switching effect on metal electrodes has been studied. For resistive switching mechanism analysis, thermal measurements including micro-thermocouples and thermoreflectance imaging techniques were used. By studying the temperature variation in the devices under different voltage biases, AlOx was found to exist at the Al/PCMO interface, and it is proposed that electrochemical reaction of AlOx is contributing to the resistive switching effect in Al-based resistive switching devices.