Ga ₂ O ₃ -Graphene Hybrid Structure for Near-Infrared Metasurface Absorber

Ga2O3 is a transparent oxide dielectric material characterized by low loss, high refractive index, and excellent chemical and thermal stability, suggesting significant potential in other spectral bands beyond ultraviolet detector and power electronics, although few studies have been reported. Herein, we employ Ga2O3 as a dielectric layer to construct a metal-insulator-metal (MIM) symmetric metasurface absorber, which achieves nearly perfect absorption of 99% in the near-infrared band, and can achieve a maximum redshift of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.009~\mu $ </tex-math></inline-formula>m to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.349~\mu $ </tex-math></inline-formula>m by changing the parameters of the upper symmetric metal array. Additionally, If the symmetry of the metal array is broken, the Fano effect will be excited, generating multiple resonance peaks in the absorption spectrum, and more than 60% of the average bandwidth absorption will be achieved in the range from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.844~\mu $ </tex-math></inline-formula>m to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.130~\mu $ </tex-math></inline-formula>m by the superposition of multiple resonance peaks. More importantly, graphene is introduced into the asymmetric structure, resulting in a dynamic modulation of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.334~\mu $ </tex-math></inline-formula>m by adjusting the Fermi energy of graphene, while the bandwidth absorption characteristics are retained. This work sheds valuable insight into the Ga2O3-based metasurface absorber, thereby paving the way for near-infrared optoelectronic devices.