Optical, Compositional and Electrical Properties of Transparent MgO Thin Film for ReRAM Devices

Abstract

Abstract The bipolar switching phenomenon is observed in the MgO-based memory cell having a metal-oxide-metal (W/MgO/Cu) structure. The MgO thin film offers a high transmittance of 86 - 88% for visible light, measured by UV-Visible spectroscopy. An optical bandgap of 4.2 eV is estimated from Tauc’s plot calculation from the absorption spectra of MgO thin film. In addition, the XPS scan on the O 1s and Mg 2p peaks reveals the types of chemical elements in the rf sputtered MgO thin film. The Mg 2p peak at 49.36 eV suggests the oxidization of Mg, and two peaks at 529.5 eV and 531.6 eV in the O 1s core level indicate the presence of lattice and non-lattice oxygen, respectively. Non-lattice oxygen is responsible for the resistive switching in oxide thin films, confirmed by electrical characterization. The I-V characteristic from the electrical measurement shows the SET and RESET transitions at 5 V and –5 V, respectively. Moreover, the experimental results provide information about Ohmic conduction in low and high resistive states. This work proposes MgO as a promising material for applications in next-generation non-volatile data storage applications.