Optical sensor

An optical sensor comprising:

• a substrate;
• and
• a first transistor, a second transistor, and a first light-shielding layer in a pixel area on the substrate,
• the first transistor including:
• a first polycrystalline silicon layer on the substrate;
• a first insulating film on the first polycrystalline silicon layer;
• a first gate electrode having a region overlapping the first polycrystalline silicon layer on the first insulating film;
• a second insulating film and a third insulating film on the first gate electrode;
• and
• a first source electrode and a first drain electrode electrically connected to the first polycrystalline silicon layer through openings in the second insulating film and the third insulating film,
• the second transistor including:
• an oxide semiconductor layer on the second insulating film;
• the third insulating film on the oxide semiconductor layer;
• a second gate electrode on the third insulating film;
• a fourth insulating film on the second gate electrode;
• and
• a second source electrode and a second drain electrode electrically connected to the oxide semiconductor layer through openings in the fourth insulating film,
• wherein
• the first light-shielding layer is provided between the first insulating film and the second insulating film and has a region overlapping the oxide semiconductor layer, and
• one of the first source electrode and the first drain electrode is electrically connected to the one of the second source electrode and the second drain electrode.