Enhanced resistive switching of silver copper iodide thin films prepared by interfacial phase formation.

Cu cations improved the electrical and chemical performance by interfacial substitution. The photochemical stability and switching efficiency of the β′-Ag 0.7 Cu 0.3 I thin layer were enhanced compared with those of pristine AgI. We compared the electrical characteristics of the β-AgI- and β′-Ag 0.7 Cu 0.3 I-based ReRAM devices depending on the applied potential. When the currents of the devices at the high-voltage from −3 to 1 V of the sweep range were collected, both devices showed a similar I–V curve, exhibiting the characteristic of a negative differential resistance effect. Significantly, at the ± 0.1 V of the sweep range, the β-AgI-based device showed ohmic behavior. In contrast, the β′-Ag 0.7 Cu 0.3 I-based device showed excellent RS behavior with high ON/OFF ratio because its electrical property was improved via interfacial chemical modification with Cu+ cations. [Display omitted] • A silver copper iodide (β′-Ag 0.7 Cu 0.3 I) thin film was successfully prepared by incorporating Cu cations into the AgI lattice at the Cu/AgI interface. • The β′-Ag 0.7 Cu 0.3 I-based device demonstrated excellent resistive switching characteristics at low operating voltages, exhibiting an ON/OFF ratio of ∼ 104. • Cu substitution at the Cu–AgI heterojunction interface is a novel way to modulate the chemical composition and improve the resistive switching uniformity. Resistive random-access memory (ReRAM), an alternative to conventional charge storage memory, employs the switching of a resistive material between high-resistance and low-resistance states, which can be generated by the formation/dissolution of metal filaments bridging the two electrodes in the cell. Silver iodide (AgI) is a promising solid electrolyte for ReRAM cells, but its application is hindered by poor photostability and low electrical conductivity. Herein, a Cu-substituted β-AgI system, β′-Ag 0.7 Cu 0.3 I, was successfully prepared via sequential deposition of a Cu metal layer onto a AgI thin film by a galvanic reaction, which induced the spontaneous incorporation of Cu+ cations into the AgI lattice. Cu substitution at the Cu–AgI heterojunction interface is a novel way to modulate the chemical composition and improve the resistive switching properties of intrinsic polycrystalline AgI thin films. We compared the resistive switching properties of a ReRAM thin film devices based on β′-Ag 0.7 Cu 0.3 I with those based on pristine β-AgI. This device exhibited enhanced performance with high ON/OFF ratio (∼104) and low working voltage compared with the β-AgI-based device. These results strongly suggest that binary metal halide materials can serve as simple model systems for the efficient formation of metal filaments and have potential low-cost, low-power memory applications. [ABSTRACT FROM AUTHOR]