Infrared thin film photodetector performance improvement using plasmonic nanostructure and ring shape lens

Currently, infrared photodetectors have attracted lots of attentions due to the wide range of industrial and non-industrial application. In this paper, a new hubrid metal-semiconductor-metal thin film infrared photodetector based on plasmonic nanostructure and ring shape optical lens has been proposed that leads to higher optical absorption. The finite difference time domain method (FDTD) is used to thoroughly investigate the interaction of proposed structure with near infrared incident wave (1.1-1.7 µm). Optical lens concentrate the incoming light on gold nanodisk array and increases the electric field magnitude on the nanodisk array. Gold nanodisk array with optimized geometrical structure leads to excitation of surface plasmon polariton and results in very high local field point inside the indium gallium arsenide layer. So, the photocarrier generation rate enhances and the structure shows higher photocurrent. According to the simulation results, proposed structure indicates 105% absorption enhancement and 140% photocurrent enhancement compared to simple photodetector strcuture.