Analysis of CMOS Photodiodes—Part II: Lateral Photoresponse

In Part I of this paper, an improved one-dimensional (1-D) analysis and a semiempirical model of quantum efficiency for CMOS photodiode was illustrated. In this part of the paper, the lateral photoresponse in CMOS photodiode arrays is investigated with test linear photodiode arrays and numerical device simulations. It is shown that the surface recombination and mobility degradation along the Si-SiO2 interface are important factors in determining the lateral photoresponse of CMOS photodiodes. The limitations of traditional analytical approaches are briefly discussed in this context, and a novel three-dimensional (3-D) analysis of lateral photoresponse is presented. Given the significant dependence of lateral photoresponse on the Si-SiO2 interface quality, an empirical characterization method is proposed as a more reliable solution to modeling lateral photoresponse.