Improved resistive switching performance of amorphous InGaZnO-based memristor with the TiO₂ insertion layer

A stable I-V repeatability memristor based on amorphous InGaZnO (a-IGZO) with a TiO2 insertion layer was investigated. Two memristive structures composed of Pt/a-IGZO/Pt and Pt/TiO2/a-IGZO/Pt were manufactured on SiO2/Si substrate by the magnetron sputtering method. The crystallization of IGZO thin films was analyzed by the XRD process under different annealing temperatures, and the results show that the thin films remain in a stable amorphous state. The resistive switching performance of the two structures was tested by the semiconductor parameter analyzer 4200-SCS at room temperature. After 30 cyclic scans, the Pt/a-IGZO/Pt structure shows signs of degeneration in its I-V cyclic characteristics. However, in the Pt/TiO2/a-IGZO/Pt structure, the cyclic characteristics of I-V are highly stable (cycles >105 sweeps) with a limiting operating current of 0.01 A. Its rectification ratio is approximately 20 at low operating voltages (+/- 1.0 V), and conductance increases (or decreases) progressively with continuous positive (or negative) voltage scans. Further analysis of the experimental energy band diagram was measured by UV-vis spectra and ultraviolet photoemission spectroscopy (UPS). The results demonstrate that the operational mechanism is the modulation of the barrier at the TiO2/a-IGZO interface, which is conducive to the stable I-V cyclic characteristic of Pt/TiO2/a-IGZO/Pt memristor.