Abstract
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.