Nickel-Assisted Laser Oxidation of WSe ₂ Layered Films for Spatially Controlled WO ₃ Patterning Process toward Resistive Memory and Molecular Sensing

High Resolution Image Download MS PowerPoint Slide A novel approach to convert a 2D WSe 2 film into a WO x film by the laser-induced oxidation process using a nickel (Ni) adsorption layer, namely Ni-assisted laser oxidation process, was demonstrated. A layer of Ni metal was deposited to absorb the heat of the laser and oxidize the top WSe 2 layer, for which an aluminum oxide (Al 2 O 3 ) layer is then deposited as a barrier layer. A continuous wave laser with a wavelength of 808 nm is selected as the laser source, as it is not absorbed by the WSe 2 layer. By introducing a patterned Ni layer, the selective oxidation process on WSe 2 into WO 3 can be achieved owing to the photothermal effects caused by the Ni layer with O 2 gas. The successful oxidation parameters, including laser powers and irradiation durations with a fixed Al 2 O 3 barrier layer thickness of 50 nm, were investigated. Resistive random-access memory (RRAM) devices fabricated using the Ni-assisted laser-oxidized WO 3 structure exhibit clear resistive switching behavior compared to the structure without the laser oxidation process. In addition, the Ni-assisted laser-oxidized WO 3 structure showed obvious surface enhanced Raman spectroscopy (SERS) signals of crystal violet (CV) and methylene blue (MB) with the lowest concentration of 10 –6 M.