In this paper, we reported increasing high resistance state (HRS) phenomenon of Al/VO x /Cu resistive random access memory (RRAM). The current of HRS became lower in current-voltage (I-V) curves and resistance of HRS gradually increased from a lower pristine sate to a higher HRS during cycling operation. Schottky emission theory was employed to investigate the HRS conduction. We found that the slope of HRS I-V curves on ln(J) and sqrt(V) plot decreased after cycling operation. According to Schottky emission theory, we concluded that generation of AlO x layer between Al electrode and VO x film was the cause of increasing HRS resistance. We finally verify the conclusion by data retention under constant voltage stress.
In this work, device cell with the Cu/VOx/Al structure was fabricated. The resistance switching performance was tested by Semiconductor Device Analyzer (Agilent B1500). This structure performs bipolar behavior. Controllable Set process and gradual Reset process, and various RLRS and RHRS could be obtained by controlling its current compliance (Icc) and reset stop voltage (Vstop), respectively. The Reset current could decrease to sub-10μA when Icc dropped to 40μA. The RHRS could be greater than 1E8 ohm with 1.5 V amplitude of applied reset voltage. This structure also has a good endurance (>1000 cycles) and reliable read disturbance times (>1000s) with 80oC ambient temperature. Local filament was observed in LRS by conducting atomic force microscope (CAFM), and Schottky barrier height modulation was obtained by I-V fitting in Reset process.
The electrical properties and conduction mechanism of the WOx-based RRAM were investigated in this work. The WOx layer was formed by DC reactive magnetron sputtering on Cu/Ti/SiO2/Si substrate at room temperature. And then RTP was done under 300oC for 30 seconds in oxygen atmosphere. The programming, reading, and reliability behaviors of the device cells were characterized detailedly. The results show that the low programming voltages for SET (1.1 V) and RESET (-0.9 V) process were achieved. The good endurance (>1000) and retention time (104 s) had been demonstrated. In addition, the device is immune to read disturb. The conduction mechanism both in ON and OFF state are oxygen vacancy conductive filament.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.