Lateral p-i-n photodetectors with 18 GHz bandwidth at 1.3 μ m wavelength and small bias voltages

Simultaneous n-Type and p-Type diffusion, compositional mixing, and formation of ohmic contacts have been used in the fabrication of lateral p-i-n photodetectors for short (0.85 μ m) and long (1.3 μ m and 1.5 μ m) wavelengths. Zinc-doped tungsten and MoGe2 are used for the p-Type and n-Type contacts, doping, and compositional mixing using rapid thermal processing at approximately=750 degrees C. With structures utilizing GaAs and Ga0.47In0.53As active regions, 3 dB bandwidths exceeding 7.5 GHz and 18.0 GHz, respectively, have been achieved at bias voltages of approximately=5 V. The corresponding dark currents are sub-100 pA and sub-10 nA and the devices exhibit a large dynamic range, near-ideal responsivity, and a high sensitivity. The performance, ease of fabrication, and process compatibility make these devices suitable for integration in digital circuits using FET.