A photodetector includes a gate electrode extending in a first direction, a ferroelectric layer on the gate electrode and maintaining a state of polarization formed by a gate voltage applied to the gate electrode, a light absorbing layer on the ferroelectric layer and extending in a second direction intersecting the gate electrode, the light absorbing layer including a two-dimensional (2D) material of a layered structure, a source electrode on the ferroelectric layer and connected to a first end of the light absorbing layer, and a drain electrode on the ferroelectric layer and connected to the a second end of the light absorbing layer.