Memristive Behavior Enabled by Amorphous–Crystalline 2D Oxide Heterostructure

Abstract

broad selection of electrical properties. In particular, ZnO thin films have attracted great interest due to their facile preparation approaches, excellent compatibility for device integration, and controllable electronic and optoelectronic behavior. [9] Their memristive behavior is primarily associated with the non-equilibrium distribution of oxygen vacancies in response to an external electrical field. This switching mechanism allows robust cycling endurance, but it is always associated with low switching speed. [10] In contrast, 2D nanomaterials offer a quantum-confined medium which can have exceptional transport properties and substantially improved memristive behavior compared to conventional bulk materials. For example, single atomic layer 2D transition metal dichalcogenide memristors exhibited high-frequency switching with an extremely low power consumption, [6,11] and memristors based on ultrathin singlecrystalline SiGe layer demonstrated significantly improved reproducibility and low energy consumption. [3] Developing memory devices with low operating voltages and low energy consumption go in the direction of a connection between instrinsically neuromorphic devices and living neurons. [12] Nevertheless, due to the unavailability of 2D oxides nanomaterials and the high entropy of introducing vacancies in 2D confined geometry, stable 2D oxide-based memristors have yet to be demonstrated. [9] Recently, ionic layer epitaxy (ILE) was developed as a versatile solution-based approach for growing large-area oxide nanosheets on a liquid surface. [13] Atomically thin single-crystalline ZnO nanosheets were synthesized with sizes over 10 µm, enabling the study of the memristor properties based on 2D metal oxides. In this work, we show extraordinary memristive behavior enabled by interfacing atomically thin single crystalline ZnO nanosheets with a few-nm thick amorphous Al 2 O 3 layer. The conduction mechanism was attributed to the classic oxygen vacancy conductive channels in the lateral transistor module. In this configuration, the ZnO nanosheet provides a 2D host of oxygen vacancies, while the amorphous Al 2 O 3 facilitates the generation and stabilization of the oxygen vacancies. The 2D heterointerface brought a new promise for flexible nonvolatile and ultralow power memory devices.Atomically thin single-crystalline ZnO nanosheets were synthesized by ILE, [13,14] in which amphiphilic molecules (oleyl sulfate) self-assembled into a monolayer at the water-air The emergence of memristive behavior in amorphous-crystalline 2D oxide heterostructures, which are synthesized by atomic layer deposition (ALD) of a few-nanometer amorphous Al 2 O 3 layers onto atomically thin single-crystallineZnO nanosheets, is demonstrated. The conduction mechanism is identified based on classic oxygen vacancy conductive channels. ZnO nanosheets provide a 2D host for oxygen vacancies, while the amorphous Al 2 O 3 facilitates the generation and stabilization of the oxygen vacancies. The conduction mechanism in the high-resistance state follo...

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A Marr's Three‐Level Analytical Framework for Neuromorphic Electronic Systems

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