Memristive Device Characteristics Engineering by Controlling the Crystallinity of Switching Layer Materials

Memristive devices (i.e., memristors) can be highly beneficial in many emerging applications that may play important roles in the future generations of electronic systems, such as bio-inspired neuromorphic computing, high density nonvolatile memory, and field programmable gate arrays. Therefore, the memristor characteristics (such as operation voltage, on/off ratio, and the number of conductance states) must be engineered carefully for different applications. Here, we demonstrate a method to modify the memristor characteristics specifically by controlling the crystallinity of the switching layer material. Through setting the temperature of atomic layer deposition, the crystallinity of deposited Al2O3 can be controlled. Using different crystalline Al2O3 as the memristor switching layer, the characteristics of the corresponding Pt/Al2O3/Ta/Pt cross-point memristors can be modified precisely. The high I-V linearity, high on/off ratio (around 108), low pulse operation voltage (2.5 V), and multilevel conductance states (314 states) of the Pt/Al2O3/Ta/Pt cross-point memristor are demonstrated. More importantly, the mechanism behind this phenomenon is studied. This work deepens our understanding of the working mechanism of memristors and paves the way for using memristors in a broad spectrum of applications.