Enhanced resistive switching performance of aluminum oxide dielectric with a low temperature solution-processed method

We reported a low-temperature solution-processed method for the fabrication of AlO_x thin films in the memory device. The detailed study is carried out to figure out the effect of varying annealing temperatures (150, 200, 250, 300, and 350 °C) on resistive switching characteristics of solution-processed aluminum oxide dielectric. The dielectric properties of AlO_x films under different annealing temperatures were evaluated by atomic force microscopy (AFM), thermogravimetric analysis-differential scanning calorimetry (TGA-DSC), X-ray diffraction (XRD), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) firstly. Then the AlO_x films were used as the switching dielectric layer for a variety of low-temperature solution-processed oxide resistive random access memory (RRAM) devices. It was found that forming voltage increased with increasing annealing temperature and forming free behavior could be achieved by 200 °C sample. No repeatable resistance switching characteristics were observed in the devices with minimum (150 °C) and maximum (350 °C) annealing temperatures. Compared with the ALD-derived AlO_x based RRAM devices in previous study, enhanced performance like small forming voltage, large resistance ratio (〈1 8 0) and narrow resistance and voltage distribution was achieved by the solution-processed AlO_x based ones at the optimized low annealing temperatures of 200 to 250 °C, which would be applied in the bionic circuit simulated by synapses and neural networks. All three samples (200, 250, and 300 °C) obtained switching endurance up to 300 cycles and data retention over 10⁴ s. Furthermore, the solution based fabrication method also has the potential in the flexible memory application due to the merit of the low-temperature process.