Analytical Modeling of Pinning Process in Pinned Photodiodes

Abstract

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 ( $\Delta \varphi _{M}$ ) and maximum electron quasi-fermi level potential variation ( $\Delta $ FP $_{M}$ ). The output of the previous pinning potential models is only an approximation of $\Delta \varphi _{M}$ . 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 $\Delta \varphi _{M}$ 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 $\Delta \varphi _{M}$ . The proposed model is verified by two previously reported experiment-based data.