Effect and Limitation of Pinned Photodiode

The pinned photodiode (PPD) is the primary technology for image sensors and used in almost all charge-coupled device image sensors and CMOS image sensors. This paper discusses the effect and limitation of PPD, especially dark current and electronic shuttering. Even when the PPD is used and silicon surface is neutralized, the proposed model explains that generation-recombination (GR) centers at the silicon surface contribute the dark current. The temperature dependence is an activation type with activation energy, E
_g
, not E
_g
/2 . The model sheds light on the importance of GR center reduction for dark current decrease even at PPD. It is also noted that the vertical overflow drain shutter combined with the PPD has potential of high-speed shuttering with small skew.