High-Speed InGaP/GaAs p-i-n Photodiodes With Wide Spectral Range

By selectively removing the GaAs cap layer on top of the InGaP/GaAs p-i-n photodiodes, a photodiode with high quantum efficiency in the 300-850-nm spectral range was realized. With antireflection coating designed for 850 nm, a quantum efficiency that is higher than 90% in the 420-850-nm range and higher than 70% in the 360-870-nm range was achieved. In addition, the photodiode, exhibiting a dark current smaller than several picoampere, has a 3-dB bandwidth higher than 9.7 GHz at the 850-nm wavelength. Since both high-efficiency and high-speed operation can be achieved, receivers based on such devices are suitable for both the 850- and 650-nm fiber communication systems.