A p-i-p-in front-illuminated Al 0.4 Ga 0.6 N-based separate absorption and multiplication solar-blind ultraviolet avalanche photodetector is proposed to enhance the optoelectronic performances by modulating polarization electric field based on physical simulations. By modulating the pAl x Ga 1−x N interlayer with low Al content, the direction of the polarization electric field could be achieved the same as that of the reverse bias in the multiplication region. The calculated results demonstrate that the designed avalanche photodetectors with a low Al-content pAl x Ga 1−x N layer would significantly reduce the breakdown voltage and enhance the optical gain compared to the conventional counterpart. The effect of modulated polarization electric field on the noise characteristics for the APDs with pAl x Ga 1−x N interlayers is investigated. Moreover, the physical mechanism of the enhanced performances for the APDs with modulated polarization field is explored by the electric field distributions and energy band profiles.

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