High-performance waveguide uni-traveling carrier photodetector based on GaAs0.5Sb0.5/InP type-II heterojunction

Heterogeneous III-V/silicon photonic integrated circuits promise to integrated dissimilar materials without compromising their own properties. InP-based high-power and high-speed In0.53Ga0.47As modified uni-traveling carrier photodiodes(UTC-PDs) heterogeneously integrated on silicon-on-insulator waveguides have been demonstrated. In this paper, we will propose a novel GaAs0.5Sb0.5/InP type-II waveguide UTC-PD. The p-type In0.53Ga0.47As absorption layer is replaced by a p-type GaAs0.5Sb0.5 layer. Due to the type-II interface between p type GaAs0.5Sb0.5 absorber and InP collector, photo-generated electrons generated in the absorption layer are injected into the collection layer with enhanced kinetic energy, which aids their transport toward the collector and minimizes the current blocking effect. Our device shows a significant improvement in the responsivity (1.14A/W) and bandwidth(40.3GHz) compared with that of waveguide UTC-PD with the same thickness of pure In0.53Ga0.47As absorber. The demonstrated type-II PD offers a record overestimated saturation current-bandwidth product 4473.3 mA.GHz . These promising results suggest that our proposed GaAs0.5Sb0.5/InP type-II waveguide UTC-PD structure can fundamentally overcome the trade-off among bandwidth, responsivity, and length of high-speed waveguide PDs.