RRAM switching mechanism

The property of PCMO RRAM memory resistors have been studied in terms of electrical pulse width, temperature dependent of resistance, trap state, and electrode effects. The PCMO material is deposited using MOD, PVD, or PLD process. The MOD PCMO is a small grain polycrystal material. The PLD PCMO is mainly having a single crystal structure, while the PVD PCMO has a large grain polycrystal structure. The experimental results clearly shown the RRAM non-volatile resistance change is neither an interface effect, nor due to field induced electro-chemical migration. In addition there is neither crystalline to polycrystalline phase change nor metallic conduction filament formation causing the resistance changes. The experimental data on the pulse width dependent of the resistance change, the temperature dependent of the resistance, and the charge transport property in PCMO with different crystalline structure lead to the conclusion that the electrical pulsed induced resistance increase is a current driven process and is due to the localization of valence electrons by electron-electron interaction. The electrical pulse induced reduction of resistance is a field driven process and is due to delocalization of localized valence electrons by high electric fields. We define the interface as the region no deeper than 1nm each side from the metal contact