Fabrication of High-Speed Photodiode with Monolithic Integrated InP Microlens

Back-illumination high-speed photodiode (PD) with monolithic integrated InP microlens was designed and fabricated. The layer structure thickness and doping concentration of the PD were optimized based on carrier transport. Taking into account the effective photosensitive area of the PD and the deviation compensation characteristics of the incident light, an InP microlens was monolithically integrated on the backside of the device. The prepared InP microlens have a diameter of 100 μm, a dome height of 18 μm, and a focal length of 114 μm, with the light spot at the focal point being tested. At a wavelength of 1310 nm, the actual measured bandwidth of the high-speed PD with monolithic integrated InP microlens reached 43 GHz, with a mesa diameter of 18 μm. Furthermore, deviation incident compensation characteristics of the integrated chip were tested and analyzed under horizontal, vertical, and different angle deviations.