Minimizing reflection and focussing of incident wave to enhance energy deposition in photodetector's active region

Geometry of grating structure has been analyzed to maximize electromagnetic energy deposition onto the active region of a silicon photodetector. The concept of Brewster angle to minimize reflection from the grating surface and a differences-in-time technique to focus incoming electromagnetic radiation on the substrate has been applied to optimize the grated structure that amplifies transmitted energy through grating-substrate interface. The computed electric field at the interface for the new grating geometry has been found to be approximately 1.5 times higher than that of a square-shape gratings reported earlier. Also the average power depositions and electric field distributions on the grating-substrate interfaces have been studied which revealed the superiority of the proposed optimum structure.