Effects of energetic ion irradiation on WSe2/SiC heterostructures

The remarkable electronic properties of layered semiconducting transition metal dichalcogenides (TMDs) make them promising candidates for next-generation ultrathin, low-power, high-speed electronics. It has been suggested that electronics based upon ultra-thin TMDs may be appropriate for use in high radiation environments such as space. Here, we present the effects of irradiation by protons, iron, and silver ions at MeV-level energies on a WSe2/6H-SiC vertical heterostructure studied using XPS and UV-Vis-NIR spectroscopy. It was found that with 2 MeV protons, a fluence of 1016 protons/cm2 was necessary to induce a significant charge transfer from SiC to WSe2, where a reduction of valence band offset was observed. Simultaneously, a new absorption edge appeared at 1.1 eV below the conduction band of SiC. The irradiation with heavy ions at 1016 ions/cm2 converts WSe2 into a mixture of WOx and Se-deficient WSe2. The valence band is also heavily altered due to oxidation and amorphization. However, these doses are in excess of the doses needed to damage TMD-based electronics due to defects generated in common dielectric and substrate materials. As such, the radiation stability of WSe2-based electronics is not expected to be limited by the radiation hardness of WSe2, but rather by the dielectric and substrate.