Electroforming-Free, Flexible, and Reliable Resistive Random-Access Memory Based on an Ultrathin TaOx Film

A flexible resistive switching (RS) memory was fabricated on a Ta/TaO x /Pt/polyimide (PI) structure with various TaO x thicknesses (5, 10, and 15 nm). The oxygen vacancy (V O ) concentrations in the TaO x films were also adjusted by controlling the oxygen partial pressure during TaO x deposition to obtain different electroforming (EF) behaviors. When the devices of Ta/TaO x /Pt/PI showed the EF-free characteristic, the reliability and endurance performance were greatly improved compared to those of devices with EF behavior. The resistive crossbar array using the thinnest (5 nm) TaO x film showed high uniformity and endurance performance up to 10 8 switching cycles even after bending to a 2 mm radius 10 000 times. However, for the EF samples, the endurance performance was much lower and involved the reset failure, even with the 5 nm TaO x film.