Crosstalk characteristic is closely correlated to higher sensitivity and higher resolution imaging of focal plane array (FPA). The electrical crosstalk of typical planar and mesa In0.53Ga0.47As/InP FPAs as a function of illumination wavelength, incidence, as well as the etching depth in the mesa structures was investigated quantitatively in detail by simulation. It was demonstrated that mesa structures possess better electrical crosstalk characteristics compared with the planar designs. Significantly, the crosstalk is lower for shorter wavelength radiation while the front-side illumination devices show better electrical crosstalk characteristics than do the back-side illuminated devices. It is ascribed to the influence of material absorption depth and the p-i junction depletion width of such structures. It was also found that the electrical crosstalk appears to be greatly suppressed when the etching depth of the mesa structure covers the entire absorption layer of the device. The results suggest design rules for InGaAs FPA with low electrical crosstalk.