Modeling of pinned photodiode for CMOS image sensor

Photodetector is the very important part of CMOS image sensors. At present, the pinned photodiodes (PPDs) are popularly used in photon-to-electricity conversion process, which can minish the dark current greatly. Therefore, it is important and necessary to construct an accurate and reasonable model before conducting research on the structure of CMOS image sensor. Here the study utilizes the minority carrier equilibrium continuity equations and semiconductor material absorption of photon to get the expression of photocurrent. By means of MATLAB, the relationship between responsibility and wavelength of pinned photodiode is found out and the results are analyzed. Finally, the model is proved to be effective by comparing the results of this model with another simulation results by Taurus Medici 2003 and Taurus Tsuprem4.