Photodetector

A photodetector comprising:

• a photodiode configured to convert light into an electric charge;
• and
• a thin-film transistor (TFT) configured to detect the electric charge,
• wherein the TFT includes
• a gate electrode,
• a source electrode,
• a drain electrode, and
• an oxide semiconductor film striding between the source electrode and the drain electrode,
• wherein the oxide semiconductor film includes
• a first region overlapping the source electrode in a plan view,
• a second region overlapping the drain electrode in the plan view, and
• a third region located between the first region and the second region, and overlapping only the gate electrode in the plan view, and
• wherein in the plan view, a width of the oxide semiconductor film in a second direction is smaller than widths of the source and drain electrodes, the second direction being perpendicular to a first direction and perpendicular to the oxide semiconductor film, the first direction being a direction passing through the individual first, second, and third regions in a shortest distance.