Investigation of modulation transfer function in InGaAs photodetector small pitch array based on three-dimensional numerical analysis

Three-dimensional numerical simulation technology was used to investigate the influence of structural and material parameters on the modulation transfer function (MTF) of lattice matched InGaAs/InP planar small pitch arrays. We found that extending depletion zone through increasing depth of diffusion junction and reducing the doping concentration in the absorption layer plays a critical role in optimizing the MTF of arrays. And it is highly worth noting that the very optimization effects become even more pronounced in smaller pitch arrays, which offers valuable references to restrain crosstalk in highly dense array and strengthen the imaging ability of large format photodetector system in future. However, the inevitable cost of deteriorating the specific detectivity should not be ignored. And hence, junction depth and doping concentration of the absorption layer need to be balanced in actual preparation. In addition, the effects of lattice temperature on MTF and crosstalk in arrays were also discussed. The inter-pixel crosstalk deteriorates seriously as rising lattice temperature. A stronger impact of lattice temperature on MTF of larger pitch arrays has been confirmed. This work offers important reference to suppress inter-pixel crosstalk in obtaining the high-resolution imaging for InGaAs photodetector focal plane array.