Modeling and Analysis of Zinc Diffusion Effect in High-Speed Modified Uni-Travelling-Carrier Photodiodes

We investigate the influence of Zinc diffusion on the electron transport and high-speed characteristics of InP based Uni-Travelling-Carrier Photodiodes (UTC-PD). By analyzing the electric field distribution and energy band structure of three types of Zinc diffusion profiles, the fundamental electron transport mechanisms inside UTC-PDs are systematically studied. We show that high speed UTC-PD performance is limited by electrical field assisted electron transport inside the absorber region, and small energy barrier from Zn diffusion during MOCVD growth can strongly impact InP UTC-PD high frequency response.