Aromatic structure degradation of single layer graphene on an amorphous silicon substrate in the presence of water, hydrogen and Extreme Ultraviolet light

Highlights: • Study mechanisms of defect formation during EUV irradiation with H₂ and H₂O. • Ring structure degradation through graphene oxidation forming enols and ketones. • Graphene oxidation slows down over time due to saturation of defect formation. • Increased H2 pressure enhances graphene oxidation during EUV irradiation. In this paper we study the reaction of water and graphene under Extreme Ultraviolet (EUV) irradiation and in the presence of hydrogen. In this work, single layer graphene (SLG) on amorphous Si as an underlying substrate was dosed with water (0.75 mL) and exposed to EUV (λ = 13.5 nm, 92 eV) with partial pressures of H₂ in the background. The results show that the aromatic structure of graphene, when exposed to EUV and H₂, breaks down into aryl ketones and enols of 1,3 di-ketone. Infrared (IR) spectroscopy shows that SLG oxidizes, with increasing H₂ pressure leading to the grain boundary edges of graphene forming ketones and carboxylic acids. In situ and post exposure analyses also reveal that EUV exposure reduces the sp² content of the graphene layer, with the sp³ content increasing, resulting in a more defective graphene layer.