This paper presents InP-based evanescently-coupled waveguide modified uni-traveling carrier photodiodes (MUTC-PDs) that achieve a breakthrough in bandwidth. The design optimization focuses on the cliff layer and waveguide layer to enhance carrier transport and optical coupling. To address parasitic capacitance, benzocyclobutene (BCB) is introduced under the PD electrodes, effectively reducing the RC time constant. Devices with sizes of 2 × 7 μm² and 2 × 10 μm² achieve 3-dB bandwidths over 220 GHz, with external responsivities of 0.161 A/W and 0.237 A/W, respectively. Notably, the 2 × 15 μm² device reaches a peak RF output power of -1.69 dBm at 215 GHz. The study demonstrates the potential for THz generation through InP photonics integrated circuits.This paper presents InP-based evanescently-coupled waveguide modified uni-traveling carrier photodiodes (MUTC-PDs) that achieve a breakthrough in bandwidth. The design optimization focuses on the cliff layer and waveguide layer to enhance carrier transport and optical coupling. To address parasitic capacitance, benzocyclobutene (BCB) is introduced under the PD electrodes, effectively reducing the RC time constant. Devices with sizes of 2 × 7 μm² and 2 × 10 μm² achieve 3-dB bandwidths over 220 GHz, with external responsivities of 0.161 A/W and 0.237 A/W, respectively. Notably, the 2 × 15 μm² device reaches a peak RF output power of -1.69 dBm at 215 GHz. The study demonstrates the potential for THz generation through InP photonics integrated circuits.