Dynamic Analysis of High-Power and High-Speed Near-Ballistic Unitraveling Carrier Photodiodes at $W$ -Band

In this letter, we demonstrate and analyze the high-speed and high-power performance of a back-illuminated near-ballistic unitraveling-carrier photodiode (PD) at TV-band. We utilize a three-port equivalent-circuit-modeling technique to show that the extracted average electron drift velocity in the whole epi-structure is around 5times10⁷ cm/s, which corresponds to an ultrahigh transit time limited bandwidth (~400 GHz). Such high internal bandwidth means that the demonstrated device can thus release the burden imposed on downscaling the device active area and epi-layer thickness for achieving ultrahigh-speed performance of PDs. With a collector thickness of 410 nm and an active area of 64 mum², we can achieve a wide 3-dB bandwidth (120 GHz), and high saturation current bandwidth product performance (120 GHz, 24.6 mA, 2952 mAGHz) under 25 Omega loading at W-band.