InP-Based Waveguide-Integrated Photodiodes With InGaAs/GaAsSb Type-II Quantum Wells and 10-GHz Bandwidth at 2 $ \mathbf {\mu }$m Wavelength

Abstract

Waveguide-integrated photodiodes with InGaAs/GaAsSb type-II quantum well absorption regions designed to absorb light at 2 $ \mu$ m are presented. A novel dual-integrated waveguide-depletion layer was used to maximize quantum efficiency in photodiodes designed with thin absorbers for high-speed optical response. Low dark currents (1 nA at $-$ 1 V) and an internal responsivity of 0.84 A/W along with a bandwidth above 10 GHz and an open eye diagram at 10 Gb/s have been demonstrated at 2 $ \mu$ m. The high-speed carrier dynamics within InGaAs/GaAsSb type-II quantum wells are explored for the first time and suggest that the transit time of the photodiode is limited by light hole escape times in the quantum wells.