High-Performance GaNAsSb/GaAs 1.55- $\mu\hbox{m}$ Waveguide Photodetector

We report on the small-signal high-frequency response of a GaNAsSb/GaAs pin waveguide photodetector at 1.55-μm wavelength. The GaNAsSb absorbing layer with 3.5% N and 18% Sb is sandwiched by GaAs-cladding layers. The device of an 8-μm ridge width and 15-μm ridge length has a dc responsivity of 0.44 A/W and an 11-GHz cutoff frequency at 5-mW optical illumination at a bias condition of -5 V. A higher cutoff frequency of 14.3-GHz is achieved on the smallest device of 4-μm ridge width and 17-μm ridge length with a responsivity of 0.2 A/W at a reverse bias condition of -1 V.