Effect of magnetron sputtering parameters and stress state of W film precursors on WSe(2) layer texture by rapid selenization

Tungsten diselenide (WSe(2)) film was obtained by rapid selenization of magnetron sputtered tungsten (W) film. To prevent WSe(2) film peeling off from the substrate during selenization, the W film was designed with a double-layer structure. The first layer was deposited at a high sputtering-gas pressure to form a loose structure, which can act as a buffer layer to release stresses caused by WSe(2) growth. The second layer was deposited naturally on the first layer to react with selenium vapour in the next step. The effect of the W film deposition parameters(such as sputtering time, sputtering-gas pressure and substrate bias voltage)on the texture and surface morphology of the WSe(2) film was studied. Shortening the sputtering time, increasing the sputtering-gas pressure or decreasing the substrate bias voltage can help synthesize WSe(2) films with more platelets embedded vertically in the matrix. The stress state of the W film influences the WSe(2) film texture. Based on the stress state of the W film, a model for growth of the WSe(2) films with different textures was proposed. The insertion direction of the van der Waals gap is a key factor for the anisotropic formation of WSe(2) film.