A method for fabricating a thin film transistor (“TFT”) device includes providing a substrate, forming a patterned amorphous silicon layer over the substrate including a pair of first regions, a second region disposed between the pair of first regions, and at least one third region, each of which being disposed between and contiguous with the second region and each of the pair of first regions, the second region including a sub-region contiguous with each of the at least one third region, forming a heat retaining layer over the substrate, irradiating the patterned amorphous silicon layer with a laser through the heat retaining layer to form a patterned crystallized silicon layer corresponding to the patterned amorphous silicon layer including a grain boundary extending substantially across a crystallized sub-region corresponding to the sub-region, and forming a patterned conductive layer over a portion of a crystallized second region of the patterned crystallized silicon layer corresponding to the second region of the patterned amorphous silicon layer.