The ultraviolet absorption of graphene in the Tamm state

Ultraviolet (UV) light trapping by monolayer graphene is of great significance in optoelectronic devices. In this work, to enhance the UV absorption of monolayer graphene, a metallic thin film-type/graphene/Bragg mirror optical structure is developed using transfer matrix methods. Our results showed that the absolute UV absorption of monolayer graphene can reach approximately 83 % at the wavelength of 270 nm, which is a 9.2-fold enhancement compared to the intrinsic value of free-standing graphene (9%). This high absorption is due to the strong field confinement of the Tamm state in the silica spacer layer. The UV absorption of graphene can be tuned by adjusting the nanostructure parameters and incident angles. Furthermore, the proposed structure is less affected by machining errors. Considering the influence of processing precision, the light absorption of graphene in this structure is higher than that in the microcavity of a photonic crystal. The results obtained in this study may find promising applications in high-performance UV-graphene optoelectronic devices, such as modulators and photodetectors, as well as in photocatalysis.