Nanometer germanium photodetector with aluminum surface plasmon antenna for enhanced photo-response

Abstract

We present theoretical design process for plasmon-enhanced photodetectors with nanometer-scale germanium area. The nontraditional plasmonic metal aluminum is employed as the material of surface plasmon antenna instead of noble metals owing to its integration compatibility with existing silicon complementary metal-oxide-semiconductor technology. The electrode/antenna is patterned with shallow concentric grating surrounding a subwavelength aperture (bull's eye structure) for concentrating and guiding strong optical intensity into an ultra-small active area. The physical modeling and geometric parameters optimization are performed based on the finite-difference time-domain method. Due to the excitation of fundamental or 2nd-order Bloch surface plasmon polaritons, high absorption can be obtained at nearinfrared wavelengths of 1310 and 800 nm.