Performance comparison of two types of silicon avalanche photodetectors based on N-well/P-substrate and P₊/N-well junctions fabricated with standard CMOS technology

We characterize and analyze silicon avalanche photodetectors (APDs) fabricated with standard complementary metal-oxide-semiconductor (CMOS) technology. Current characteristics, responsivity, avalanche gain, and photodetection bandwidth of CMOS-APDs based on two types of PN junctions, N-well/P-substrate and P⁺/N-well junctions, are compared and analyzed. It is demonstrated that the CMOS-APD using the P⁺/N-well junction has higher responsivity as well as higher photodetection bandwidth than N-well/P-substrate. In addition, the important factors influencing CMOS-APD performance are clarified from this investigation.