Asymmetric resistive switching by anion out-diffusion mechanism in transparent Al/ZnO/ITO heterostructure for memristor applications

In this report, the monovalent cations of sodium and potassium are doped into the ZnO matrix to explore for resistive switching. The structural analysis confirms that Na+ and K+ cations are incorporated into the interstitial sites of ZnO lattice. The Na+ and K+ doped ZnO thin films (NZO and KZO) have exhibited improved transparency slightly higher than 80 % for the wavelength range 400-1000 nm. Hall and impedance measurements confirms that resistance of the thin films increased after incorporation of Na+ and K+ cations into the ZnO lattice. The fabricated NZO and KZO thin films-based memory devices exhibited bipolar resistive switching phenomenon with excellent ON/OFF ratio of 104, endurance of ~ 100 cycles, and charge retention of 104 s in both the resistive states. These results imply that NZO and KZO films to have enormous potential to serve as an efficient resistive switching device.