Pinned Buried PIN Photodiode Type Solar Cell

This paper reviews the origin of Pinned Buried Photodiode and its historical development efforts. Three original Japanese Patent Applications filed by Hagiwara at Sony in 1975 are explained in details which defined the first triple junction type Pinned Buried Photo diode with the in-pixel vertical overflow drain (VOD) function with the electrical shutter capability, realizing the completely film-free and mechanical-parts-free all-digital solid-state image sensors. It is shown that the conventional PN junction depletion region is not the only place to have a barrier potential needed for photo electron hole pair separation. A clever doping-engineering of the pinned surface P+ P hole accumulation region can also create the surface barrier electric field to enhance drastically the photo electron and hole pair separations to increase the short-wave blue light sensitivity. It is concluded that this surface P+P doping-engineering possibly creates Pinned Buried PIN Photo diode Type Solar Cell with a better quantum efficiency.