Patent ID: 8653618
Filing Date: 2014-02-18
Classification: H01L

Abstract:
1. A photo detector configured to absorb light in a unit pixel of an image sensor transforming the absorbed light to an electrical signal, comprising: a light-absorbing part configured to absorb light by being formed in a floated structure; an oxide film having one surface thereof being in contact with the light-absorbing part; a source being in contact with one side of the other surface of the oxide film and separated from the light-absorbing part with the oxide film therebetween; a drain facing the source so as to be in contact with the other side of the other surface of the oxide film and separated from the light-absorbing part with the oxide film therebetween; and a channel formed between the source and the drain and configured to form flow of an electric current between the source and drain, wherein the light-absorbing part is doped with first type impurities, and the source and the drain are doped with second type impurities, wherein the light-absorbing part is insulated from the source and the drain by the oxide film, wherein the light-absorbing part comprises: a first light-absorbing part being in contact with the oxide film and configured to absorb red light of the absorbed light; a second light-absorbing part formed above the first light-absorbing part and configured to absorb green light of the absorbed light; a third light-absorbing part formed above the second light-absorbing part and configured to absorb blue light of the absorbed light; a first insulation layer formed in between the first light-absorbing part and the second light-absorbing part; and a second insulation layer formed in between the second light-absorbing part and the third light-absorbing part, wherein electron-hole pairs are formed in the light-absorbing part by light incident to the light-absorbing part, tunneling occurs through the oxide film between at least one of the source and the drain and the light-absorbing part, electrons of the electron-hole pairs are discharged to at least one of the source and the drain from the light-absorbing part by the tunneling, and flow of electric current of the channel is controlled by a change in the quantity of electric charge of the light-absorbing part by the discharge of the electrons, and wherein the light-absorbing part is formed of poly-silicon.