Supplementary Information.pdf

Researchers developed mid-infrared semimetal polarization detectors with configurable polarity transition, utilizing few-layer graphene and metallic nanoantennas. Theoretical analysis and numerical implementation of the modeling were conducted to understand the nanoantennas-mediated photocurrent flow in graphene. The model considers both hydrodynamic and diffusive transport of electrons, including effects such as Joule heating, Peltier cooling, and current crowding. The equations for charge velocity in graphene were derived, taking into account the force resulting from the pressure gradient, electric potential gradient, and source term of the fluid. The potential was recovered from the velocity distribution, and the source term was assumed to scale with the electrical field intensity and the gradient of the Seebeck coefficient. Numerical implementation involved estimating the Seebeck coefficient profile, calculating the gradient of Seebeck coefficients, and obtaining the near field of nanoantennas under polarized illumination using FDTD simulation. The effective driving term was calculated by multiplying the gradient of Seebeck coefficients with the squared electrical field intensity, showing that local photocurrents are mainly generated at the edges of nanoantennas.