FDTD simulation of local electric field enhancement caused by nanoscale roughness comprising of different metals under the solar spectrum

This study enhanced the electric field intensity in a crater structure according to the roughness size and metal type. We were able to explore how the electric field is distributed using a finite-difference time-domain (FDTD) for three-dimensional crater with various types and sizes of roughness. Based on this calculation, the transmittance, reflectance, and absorptance spectra were analysed. Among the various transition metal types and sizes, the strongest local electric field occurred for an Ag roughness with a size of 60 nm. Furthermore, to analyse the solar spectrum, a blackbody radiation curve based on Planck’s law was applied to an absorptance of 250–2500 nm wavelength according to the background index.