Analysis of Dark Currents and Minimum Detectable Powers for InGaAsP Optical Receivers

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Abstract
The dark current for 1.3 µm InGaAsP and In0.53Ga0.47As avalanche photodiodes was found to consist of two components: (1) a band-to-band tunneling current observed near the breakdown voltage and (2) a generation current at a lower bias voltage. An extensive estimation of the dark current for both diodes is made over a wide range of the donor density for epitaxial wafers on the basis of experimental results. Calculations of the minimum detectable power are made for InGaAsP optical receivers, including avalanche photodiodes and PIN diodes, as a function of various parameters according to the theory by Smith et al. A comparison between minimum detectable powers for avalanche photodiodes and PIN diodes reveals that for λ=1.3 µm, 1.3 µm InGaAsP avalanche photodiodes can provide a better sensitivity than In0.53Ga0.47As PIN diodes whereas for λ=1.5 µm, In0.53Ga0.47As PIN diodes can provide a sensitivity comparable to or better than In0.53Ga0.47As avalanche photodiodes.