Patent ID: 8519397

Claim:
A photoelectric conversion element comprising: a first gate electrode; a first gate insulating layer covering the first gate electrode; a crystalline semiconductor layer over the first gate insulating layer; an amorphous semiconductor layer over and in contact with the crystalline semiconductor layer; impurity semiconductor layers over the amorphous semiconductor layer, the impurity semiconductor layers provided apart from each other; a source electrode and a drain electrode over and in contact with the impurity semiconductor layers; a second gate insulating layer over the source electrode and the drain electrode, a part of the second gate insulating layer covering a portion having the crystalline semiconductor layer and the amorphous semiconductor layer, where the impurity semiconductor layers are not provided; and a second gate electrode over the second gate insulating layer, wherein a light-receiving portion is provided in the portion having the crystalline semiconductor layer and the amorphous semiconductor layer, where the impurity semiconductor layers are not provided, wherein the first gate electrode includes a light-shielding material and entirely overlaps with the crystalline semiconductor layer and the amorphous semiconductor layer, wherein the second gate electrode includes a light-transmitting material and overlaps with the light-receiving portion, and wherein the first gate electrode is electrically connected to one of the source electrode and the drain electrode.