I want to use FDTD to simulate black phosphorus absorption A. Since black phosphorus is not in the material library, I add 3D new material by looking for the permittivity. The references are 'Jalaei, S., Karamdel, J. and Ghalami-Bavil-Olyaee, H. (2020), Mid-Infrared Photodetector Based on Selenium-Doped Black Phosphorus. Phys. Status Solidi A, 217: 2000483'. Then, simulation is carried out by referring to "Black antenna Mid-Infrared Photodetector with Circular Au/Pd Antennas". However, compared with BP photodetector without antenna, the negative performance of BP detector with antenna is worse. The absorption rate goes down. I'm puzzled. Can anyone help me out? Thanks!