Experimental Determination of the Tunable Threshold Voltage Characteristics in a AgxTe1-x/Al2O3/TiO2-Based Hybrid Memory Device

We demonstrate a hybrid memory device with both memory and selector characteristics by using Al2O3 (memory) and TiO2 (selector) layers. The proposed device exhibits tunable threshold voltage characteristics based on the length of the residual conductive filament (CF) in the Al2O3 layer. To confirm the switching characteristics, the stability of the metallic CFs in each of the Al2O3 and TiO2 layers is investigated via electrical measurements. Our findings reveal that the CF in the TiO2 layer, which acts as a selector device, spontaneously ruptures. In contrast, a stable residual CF is observed in the Al2O3 layer, which acts as a memory device. Furthermore, we confirm that the tunable threshold voltage characteristics relate to the different tunneling gap distance from the residual CF in Al2O3. These results enable the hybrid memory device to achieve a high on-off ratio, high selectivity, and low leakage current without integrating an additional selector device, thereby enabling implementation of a high-density three-dimensional cross-point array.