A threshold resistive switching (RS) device concurrently demonstrating analog memristive property with mesoporous silica-titania (m-ST) nanocomposites is introduced in this study. The nanostructured m-ST layer in an Al/m-ST/Pt device was constructed by facile soft templating of evaporation-induced self-assembly (EISA) method to demonstrate nonlinear threshold RS behaviors accompanying with discrete synaptic characteristics along with adaptive motions. The EISA layer was composed of well-ordered mesopores (∼10 nm), where paths of electrical currents could be controllably guided and sequentially activated by repeated voltage sweeps. The combinational memristive behavior accompanying the shift of threshold voltage (Vth) could implicate concurrent performances of threshold RS and selection diode devices. In addition, synaptic functionalities of long-term potentiation and depression were characterized by variations of pulse timing width (7-100 ms). Physical and chemical features of the m-ST were analyzed with Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy, and optical microscopy to investigate the unique origin of dual operation modes of the device. The m-ST synaptic device could have potential for further development of a hybrid selection diode having both a low sneaky current loss and memristive characteristics accomplishing low level of cross-talk between RS devices.
Keywords: analog memristive switching; depression; mesoporous silica−titania (m-ST) nanocomposite; potentiation; soft templating; synaptic device; threshold effect.