InGaAs/InGaAsP Avalanche Photodiodes and Analysis of Internal Quantum Efficiency

Abstract

New avalanche photodiodes designed in such a way as to have the In_0.53Ga_0.47As alloy as a light-absorption layer and the 1.1 µm InGaAsP quaternary alloy as a carrier-acceleration layer have been fabricated. The resulting photodiodes exhibit a spectral response over a wide wavelength range from 1.1 to 1.6 µm, with a peak external quantum efficiency of 60% at λ=1.6 µm; and the maximum avalanche gain is about 6 when measured at the initial photocurrent of 10 µA. The theory of hot carriers allows us to investigate punch-through phenomena occuring in heterostructure avalanche photodiodes. According to our theory, the electrical field at the heterointerface required for an internal quantum efficiency of 90% is at least 6×10⁴ V/cm for InGaAs/InGaAsP avalanche photodiodes, and 1×10⁵ V/cm for InGaAs/InP avalanche photodiodes. Optimum designs for both avalanche photodiodes are discussed in greater detail. on the basis of theoretical and experimental results.