Modification of the Electronic Transport in Atomically Thin WSe₂ by Oxidation

Atomically thin tungsten diselenide (WSe₂) is a promising 2D semiconductor for nanoelectronics and optoelectronics. Using UV ozone and low-power O₂ plasma treatments, it is demonstrated that the formation of WSe_2(1−x)O_2x (WSe_yO_x) leads to hysteretic behavior in vertical transport measurements and also enables to an improvement in the p-type transfer characteristics in lateral transport measurements. The amount of oxidation correlates well with the resistive switch behavior in oxidized WSe₂/graphene, and WSe_yO_x formation under the electrical contact of the horizontal devices leads to increased p-branch on/off by 100×. In addition to its effect for residue removal, oxidation on field effect transistor channel also helps mitigate n-type dominated transfer characteristics of WSe₂ commonly seen on sapphire. It is demonstrated that light oxidation of WSe₂ is a multifunctional post-growth treatment that enables vertical resistive switch junctions, contact improvement, and continuous tuning of transistor transport properties.