850-nm Edge-Illuminated Si Photodiodes Fabricated With CMOS-MEMS Technology

This letter examines edge-illuminated silicon photodiodes (PDs) fabricated using standard CMOS technology operated at 850-nm wavelength. A micro-electro-mechanical systems (MEMS) process was employed to expose the illuminated surface and achieve edge illumination. A single-mode lensed fiber is employed to inject light into the depletion region of the PD directly, limiting and reducing the diffusive carriers within the bulk Si substrate. Through employing this procedure, this letter achieved a superior performance in the 3-dB bandwidth compared with that yielded by vertically illuminated PDs. The 5.4 GHz high bandwidth was obtained using an edge-illuminated PD with a 20 μm× 15.6 μm active region.