A method of fabricating a thin film transistor includes patterning the amorphous semiconductor layer to form an amorphous semiconductor layer pattern, forming a gate electrode corresponding to the amorphous semiconductor layer pattern on a gate insulating layer, forming an interlayer insulating layer on the entire surface of the substrate, forming a first contact hole partially exposing the amorphous semiconductor layer pattern, forming a second contact hole partially exposing the gate electrode, and forming a metal layer on the entire surface of the substrate. The method also includes applying an electrical field to the metal layer such that a semiconductor layer is formed by crystallization of the amorphous semiconductor layer pattern, and patterning the metal layer to form source and drain electrodes that are insulated from the gate electrode and that are electrically connected with the semiconductor layer through the first contact hole.