Photothermal Lasing-Assisted Synthesis of 2D Metal-Organic Framework and Its Application to Memory Device

Abstract

Resistive random access memory (RRAM) has attracted as candidate in the next generation of non-volatile memory device due to its low power consumption, fast write/erase speed, and high CMOS compatibility 1–3. At present, among various materials, metal-organic frameworks (MOFs) are significantly attracting attention as promising materials for data storage applications due to their advantages of highly ordered pores, large surface area, tunable structure, and subsequent controllable function 4–6. However, it is difficult to apply MOF to RRAM, because synthesis time is generally long and additional step is needed to form the MOF into a thin film. Therefore, there is a need for a new method for synthesizing MOF in the form of a thin film simply and fast. In this work, we simply and fast synthesized a 2D MOF nanosheets, Cu(BDC), in the form of thin film using laser process. The dissolved ligand (terephthalic acid) in the N,N-dimethylformamide (DMF) is dropped on the Cu thin film and then irradiate the laser beam on the active spot. Photon energy of laser is absorbed in the Cu metal film, which generate the photothermal effect. This photothermal effect oxides the Cu atom into Cu ion and the oxidized Cu ions are used as metal source of Cu(BDC). This process simply and quickly transforms the Cu thin film into a Cu(BDC) thin film that can act an active layer of RRAM. The suggested method not only is finished in minutes, but also does not needed additional process step of transferring the MOF onto the thin film. The fabricated 2D MOF based-RRAM shows a typical bipolar switching behavior. Our device also exhibits a high on/off ratio (>103), low set/reset voltages (1 V > in SET and -0.5 V > in RESET), and long retention (1×104 s). Therefore, our research suggests a simple and rapid synthesis method of MOFs in the form of a thin film by using laser process and demonstrates applicability 2D MOF fabricated by laser process for the non-volatile memory device. Figure Caption Figure (a) Schematics of synthesis of metal-organic frameworks (MOFs) using laser process. (b) Scanning electron microscopy (SEM) image of Cu(BDC) thin film surface. (c) Transmission electron microscopy (TEM) image of single Cu(BDC) nanosheet. (d) Current-voltage (I-V) curve for 2D MOF based-RRAM device. (e) Retention tests of 2D MOF based-RRAM device. Figure 1