Analytical Modeling of Pinning Process in Pinned Photodiodes

In this paper, the pinning process of pinned photodiodes (PPDs) is described by a new analytical model, assuming the PPD to be composed of inner and junction regions. There are two definitions of the pinning potential: maximum conduction band potential variation (Delta phi(M)) and maximum electron quasi-fermi level potential variation (Delta FPM). The output of the previous pinning potential models is only an approximation of Delta phi(M). In this paper, a comprehensive model is proposed in which both aforementioned definitions of pinning potential can be achieved analytically. The proposed model is a system of equations relating PPD's main characteristics such as Delta phi(M) and equilibrium full-well capacity to other main PPD parameters such as PPD spatial dimensions, impurity dopant concentrations, maximum inner region potential, and remnant carrier population at Delta phi(M). The proposed model is verified by two previously reported experiment-based data.