Modification of the Electronic Transport in Atomically Thin WSe 2 by Oxidation

Atomically thin tungsten diselenide (WSe 2 ) is a promising 2D semiconductor for nanoelectronics and optoelectronics. Using UV ozone and low‐power O 2 plasma treatments, it is demonstrated that the formation of WSe 2(1− x ) O 2 x (WSe y O 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 WSe 2 /graphene, and WSe y O 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 WSe 2 commonly seen on sapphire. It is demonstrated that light oxidation of WSe 2 is a multifunctional post‐growth treatment that enables vertical resistive switch junctions, contact improvement, and continuous tuning of transistor transport properties.