Fermi level modulation for enhanced graphene-based ultra-sensitive gas detection

The optimization of Fermi level absorptance above the Dirac point in graphene is crucial for enhancing its gas sensing capabilities. Graphene's exceptional electrical and optical properties make it highly suitable for optoelectronics and sensing applications. This study examines the relationship between the Fermi level and graphene's optical absorptance, particularly at 0.2 eV, to maximize its interaction with electromagnetic radiation. Simulations were conducted across 0–5 THz frequencies, analyzing the impact of substrate thickness and Fermi energy. Results indicate that higher Fermi levels significantly enhance absorptance, with peak values of 0.99826 at 0.5 eV for a 39 μm substrate. Notably, at 0.2 eV, competitive absorptance is observed with a 29 μm substrate, highlighting its relevance for gas sensing. Further optimization explored the effects of rotation angle and unit cell width, revealing that a 55° rotation maximizes absorptance at 0.98384. Structural modifications also influence absorption across frequencies. This research establishes a framework for tuning graphene's absorptance at 0.2 eV, crucial for improving the sensitivity of gas sensors. The findings hold significance for developing advanced optoelectronic devices in environmental monitoring, healthcare, and industrial applications, where Fermi level tuning can enhance performance.