Resistance Switching Memory Characteristics of La-Doped SrTiO3 Multilayer Chip
The research team moved on to the next step; to measure resistance memory characteristics in the states of high resistance and low resistance at temperatures ranging from the room temperature to 125°C. The measurement was made through switching to each resistance state, followed by reading the resistance values at -10V at 60 second intervals. Figure 4 shows that there was a resistance variance of one digit and greater between high resistance and low resistance after five hours in the room temperature, thereby clearly showing that this chip had long lasting memory performance, i.e. nonvolatility. However, though the memory performance is stable in the high resistance state, as temperatures increase and time passes by, it was noted that the low resistance state changes to the high resistance state; at 125°C the resistance value in the low resistance state becomes the same resistance as in the high resistance state 160 minutes later. In short, as temperatures increase, memory performance deteriorates, so it will be inevitable to improve the memory characteristics in the low resistance state in order to use the chip in actual devices. These memory performance issues in the low resistance state have been confirmed in a Schottky contact type thin ReRAM device comprised of Pt electrodes and a conductive SrTiO3 single crystal. Certain states initiated by the electric field seem to have returned to the beginning state gradually, and it will be necessary to clarify the original cause of resistance state changes in order to improve performance characteristics.
Fig. 4 Resistance memory performances of high resistance and low resistance in several temperatures