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 WO_x 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.