Semiconductor element

Patent Granted A thin film transistor (1) is provided by forming a gate electrode (3) in a prescribed shape on an insulating substrate (2), then, laminating a gate insulating film (4) on the insulating substrate, and laminating a semiconductor layer (5) made of polycrystalline ZnO on the gate insulating film (14). By immersing a semiconductor layer (5) in a solution wherein an impurity material is dissolved, a grain boundary portion of the polycrystalline ZnO film is selectively doped with the impurity material.