Memristor devices have been rapidly emerging as a promising candidate in the field of non-volatile memory devices. There are a wide range of applications such as non-volatile random access memory, dynamic random access memory, image processing, flash memory, neural networks, and artificial intelligence. In recent years, many new materials for memristors have been investigated including metal-oxides due to their potential for high-density integration, high endurance, fast switching behavior, low power consumption and simple structure. Among the promising binary transition metal oxide materials, such as nickel oxide, zirconium oxide, zinc oxide, hafnium oxide, and Ta₂O₅, TiO₂ films are extensively used to fabricate nonvolatile memristor devices due to its simple structure and compatibility with CMOS integration processes. Recently, ZnO has been widely used for various applications due to its good electrical conductivity, wide band gape (3.37 eV), high exciton binding energy (~60 meV), low cost, nontoxicity, high mechanical and thermal stability. When doped with Aluminum ZnO grown via atomic layer deposition (ALD) has been reported to show resistivity values ranging from insulating to on the order of 10⁻³ Ω·cm, which is suitable for memory device electrodes.

Many methods are available for synthesis of thin films such as magnetron sputtering, pulsed laser deposition, thermal oxidation, electrodeposition, chemical vapor deposition, sol gel chemical reaction, and atomic layer deposition. ALD technique is considered promising for potential application in the preparation of memristors based on active TiO₂ layers. The ALD is a self-limiting technique that allows one atomic layer growth for each growth cycle. ALD can precisely control the film layer thickness, stoichiometry, composition, uniformity, and sharp interfaces. ALD also shows perfect conformal coverage when it deposits thin film on complex surface structures. Therefore, ALD is considered as a novel and competitive method to deposit MIM memory structures. To create such MIM devices, first a transparent Al:ZnO film was grown on a Si wafer as a transparent bottom electrode followed by an active layer of TiO₂ film. Then the top contact layer consisting of Al:ZnO was deposited in-situ on the TiO₂ layer to complete the memristor structure. All the thin films in the memristor structure were synthesized sequentially by ALD technology.

Several physical characterization techniques have been utilized to analyze the ALD TiO₂ thin films of memory devices. The crystal structure was determined by X-ray diffraction (XRD). The film morphology was studied by field emission scanning electron microscopy (FE-SEM). The surface roughness was measured by atomic force microscopy (AFM). The electric properties were tested by a semiconductor parametric analyzer. The results demonstrate promising memristive properties of synthesized ALD TiO₂-Based Memristors sandwhiched between Al:ZnO electrical contacts.