Ionic Transport Barrier Tuning by Composition in Pr1–xCaxMnO3-Based Selector-Less RRAM and Its Effect on Memory Performance.

Selector-less resistive random-access memory (RRAM) devices require high nonlinearity (NL) in low-resistance state current ( ${I}_{\textsf {LRS}}$ ). In this paper, we investigate the effect of composition (here, Ca%)-dependent material properties, viz., ion migration barrier, and thermal conductivity, on memory performance of recently demonstrated Pr1–xCaxMnO3-based selector-less RRAM with high NL. First, the NL increases as “ $\mathit {x}$ ” decreases. This is attributed to higher self-heating in $\textsf {PCMO}{(}\mathit {x}{)}$ films as composition-dependent thermal conductivity ( $\kappa $ ) decreases as “ $\mathit {x}$ ” is decreased. This enables selector-less operation. Second, larger memory window is observed as “ $\mathit {x}$ ” increases due to decrease in the voltage required for onset of RESET process (i.e., $V_{\textsf {MIN, RESET}}$ ) as “ $\mathit {x}$ ” is increased. Lower $V_{\textsf {MIN, RESET}}$ at higher “ $\mathit {x}$ ” is due to higher oxygen-ion conductivity attributed to lower migration barrier ( ${E}_{m}$ ). Third, retention is measured at different temperatures to extract composition-dependent ${E}_{m}$. The poor memory retention performance for $\mathit {x}= 1$ is consistent with lower ${E}_{m}$ estimated. Finally, enhanced endurance is observed for lower ${E}_{m}$ due to low-energy requirement for switching. Based on these observations, an interrelation between ${E}_{m}$ , retention, and endurance is established. Therefore, an interplay of composition-dependent thermal conductivity and oxygen-ion migration barrier enables tunable memory characteristics in Pr1–xCaxMnO3-based RRAM. [ABSTRACT FROM AUTHOR]