A thin film transistor includes a channel layer of a specific shape, a thermal gradient inducer body, a gate insulating film, a gate electrode and an interlayer insulating film, a source electrode and a drain electrode. The channel layer is formed on a substrate. The channel layer has a nucleation region and a crystal end. The thermal gradient inducer body partially circumscribes the channel layer. The gate insulating film is formed on the substrate, and the channel layer is at least partially covered with the gate insulating film. The gate electrode is formed on the gate insulating film. The interlayer insulating film is formed on the gate insulating film, and the gate electrode is at least partially covered with the interlayer insulating film. The source electrode and the drain electrode are formed on the interlayer insulating film, passed through the gate insulating film and the interlayer insulating film, and electrically connected to the channel layer.