Compliance current dependent multilevel resistive switching in Titanium dioxide nanosheet based memory devices

Abstract

The rise of two-dimensional (2D) materials has unveiled numerous potentialities in future logic and memory devices. In this work, a resistive switching memory device based on 2D Titanium dioxide nanosheet (TiO₂ NS) is fabricated with a capacitor-like device structure in which TiO₂ NS is sandwiched between silver (Ag) and Fluorine-doped tin oxide (FTO) electrodes. The spin-coating method is used to coat the hydrothermally synthesized TiO₂ NS on the FTO substrate and then silver paint is used as top contact to complete the device Ag/TiO₂ NS/FTO. Here, TiO₂ NS based resistive switching device also called as memristor shows co-existence of bipolar and unipolar resistive switching depending on the voltage sweep direction. The device is suitable for memory applications as its ON/OFF current ratio is of the order 10². The memory device shows 24 multiple resistive states (equivalent to 4.5 bits), which are obtained by tuning the compliance current from 0.2 to 4.8 mA. The multilevel resistive switching (RS) realized is attributed to the evolution and rupture of conductive filament in the TiO₂ NS. A retention test for multiple resistive states is conducted and it shows a stability up to 5 × 10³ s. The device also showed good endurance for 5 × 10³ cycles without any fluctuations in performance.