A High-Speed and High-Saturation Output-Modified Uni-Traveling-Carrier Photodiode (MUTC-PD) with an Electric-Field Regulation Layer

To alleviate the trade-off between high-speed responses and RF output capability in modified uni-traveling-carrier photodiodes (MUTC-PDs), an MUTC-PD incorporating an electric-field regulation layer (EFRL-MUTC-PD) is proposed. A 20 nm EFRL is inserted between the PD’s collector layer and its cliff layer to tailor the electric-field distribution in the collector layer, thereby enabling electron transport near the peak drift velocity under high-photocurrent operation. Simulation results indicate that the optimal doping concentration of the EFRL is 1×1016 cm−3. For an 8 µm diameter device operated at a bias voltage of −4 V and a photocurrent of 15 mA, the simulation predicts a 3 dB bandwidth of 130 GHz and a transit-time-limited bandwidth of 162 GHz, corresponding to a 9.3% improvement in the simulated 3 dB bandwidth compared with a conventional MUTC-PD. In addition, the simulated RF output power reaches 11.54 dBm at 130 GHz under the adopted simulation assumptions.