Thick Absorption Layer Uni-Traveling-Carrier Photodiodes With High Responsivity, High Speed, and High Saturation Power

High responsivity backside-illuminated uni-traveling-carrier photodiodes (PDs) with a 1.2-mum-thick p-doped absorption layer are demonstrated. The fabricated PDs achieve simultaneously high speed, high responsivity, and good linearity under high-power operation. The measured responsivity at 1.55 mum is larger than 0.83 A/W at low photocurrent and increases up to 1 A/W at 75 mA. The measured bandwidth increases from 9 GHz at 1 mA up to 24 and 29 GHz at 50 mA, for 25- and 20-mum-diameter PDs, respectively. Good linearity is demonstrated with a third-order intercept point of 30 dBm at 10 GHz and 50 mA.