Analysis of multiple physical fields and the study of optimal design method for PCA

Terahertz waves with large absolute bandwidth resources have a wide range of potential applications in communications, but low incident field strengths limit its radiation efficiency. Extraordinary Optical Transmission (EOT) causes the transmittance spectrum of light to show transmission peaks at some specific wavelengths that are inconsistent with classical theory. The electric field strength at the photoconductive antenna (PCA) electrode can be enhanced by EOT, thereby improving the radiation efficiency of photoelectric conversion. In this work, we etched rectangular grooves and small hole structures at appropriate locations on the grating electrodes, and investigated the effects of the size and location of the small holes on the transmittance. The simulation results show that the peak electric field of the metal electrode structure based on the EOT design reaches 1.67 × 10 7 V/m, and the localized electric field is increased by a factor of 4.05 compared with that of the non-slotted grating electrodes. The peak electric field values are input into the developed multi-physics model, and the results show that the peak photocurrent of the improved terahertz PCA is 7.1 times higher than that of the conventional one. By designing and analyzing the effect of the grating electrode structure of an EOT-based metal on the local electric field on the semiconductor surface, a method for the radiation efficiency of photocarrier generation is proposed. This is of great significance to promote the further application of terahertz PCA.