Integration of CMOS avalanche photodiodes evaluation and comparison of their global performances

This paper presents the design of two avalanche photodiodes (APDs) in standard 0.35 μm CMOS technology. Simulations with SILVACO suite allowed the design optimisation, the architectures to be validated and the global performances to be predicted. Two kinds of guard ring structures have been developed, simulated and validated. The P⁺N APD presents the best reponsivity with a peak around 550 nm. The N⁺P APD presents a peak of responsivity around 450 nm. At the opposite, the excess noise factor is better for the N⁺P structure. Finally, when biased at -6V and for λ = 450 nm the photoelectric gain of the N⁺P structure is equal to 100 whereas the P⁺N structure one is equal to 60 at λ = 550 nm.