Stacked image sensor using chlorine-doped crystalline selenium photoconversion layer composed of size-controlled polycrystalline particles

We demonstrate a stacked complementary metal-oxide semiconductor (CMOS) image sensor overlaid with a chlorine (Cl)-doped crystalline selenium (c-Se) photoconversion layer. The size of the polycrystalline particles (grains) of c-Se, which is strongly related to dark current pattern noise, is controlled by Cl doping to c-Se; hence, the resulting device provides clear images. Furthermore, avalanche multiplication was successfully observed in a Cl-doped c-Se film fabricated on a glass substrate at a relatively low applied voltage.