Dopant selection rules for desired electronic structure and vacancy formation characteristics of TiO2 resistive memory

Doping has often been considered for performance improvement of resistive memories (ReRAM), but the effects of many different dopants have not been distinguished. To obtain a systematic understanding of doping effects, density functional theory calculations are performed to investigate 9 metal dopants in TiO2 ReRAM. The dopants' effects on both electronic structures and vacancy-formation stability of single vacancy and conductive filament structures are discussed in detail. Trends in the physical properties using various dopants are revealed and well explained by valence-electron-based rules. Their implications to resistive switching suggest that forming/switching characteristics can be adjusted continuously by valence-based dopant selection.