US Patent 7755142 Thin-film transistor and image display device

In either of a source side and a drain side of an insular semiconductor thin film, a gate electrode is extended without a break along the contour of the insular semiconductor thin film to provide a branch closed circuit, thereby removing a current component path to server as a sub-channel in the edge of the insular semiconductor thin film, in order to eliminate current components due to the concentration of a gate electric field in silicon thin-film edges occurring in edges of an insular semiconductor thin film of top gate type thin-film transistors and a shift of threshold due to fixed charges in the periphery of the silicon thin-file edges.