Design of UTC- PD With Nanoscale Optical Microstructures

In this article, we report a uni-traveling-carrier photodiode (UTC-PD) incorporating nanoscale optical microstructures. We design a waveguide containing scattering structure for the UTC-PD to convert incident light from vertical incidence to lateral propagation and to constrain the scattered light within the absorption layer of the UTC-PD. In this way, the proposed UTC-PD can have an operating performance like that of a waveguide type PD under vertical light incidence, and its responsivity will increase. The ideal responsivity of the designed UTC-PD with 200nm thick absorption layer after optimization can reach 0.33A/W, which is 50% higher than that without a scattering structure.