Analytical modeling of a high-performance near-ballistic uni-traveling-carrier photodiode at a 1.55-μm wavelength

In this letter, we developed an analytical equivalent circuit model, which includes the resistance-capacitance-delay time and carrier transport time, to investigate the distinct dynamic performance of the near-ballistic uni-traveling-carrier photodiode (NBUTC-PD). This device, in which the structure of the collector of the UTGPD is modified, can achieve excellent performance at a 1.55-mu m wavelength. According to the measured frequency responses of the scattering (S) parameters of NBUTC-PD and detailed device-modeling, the observed significant reduction of the device capacitance and the enhancement of the net optical-to-electrical bandwidth under high-power operation can be attributed to the unique near-ballistic-transport property of the photogenerated electron, which has never been observed in the traditional high-speed high-power photodiode.