Limitation of SPADs quantum efficiency due to the dopants concentration gradient

Single-photon avalanche diodes are highly sensitive devices capable of registering the arrival of an individual photon. They are biased beyond breakdown voltage, and thus the electron-hole pairs generated by any incident photon is accelerated by the strong electric field triggering an avalanche current. This paper examines the role of the dopants concentration gradient in the gathering of photons in these devices, and how it can be engineered to maximize quantum efficiency and explain his role to minimize undesirable effects like crosstalk.