Patent ID: 8779426

Claim:
A thin film transistor comprising: a gate electrode arranged on a substrate; a source electrode and a drain electrode spaced from each other on the substrate; a gate insulating film to insulate the gate electrode from the source electrode and the drain electrode; and a semiconductor layer insulated from the gate electrode by the gate insulating film, the semiconductor layer including a first region and a second region, the semiconductor layer made of (In 2 O 3 ) x (Ga 2 O 3 ) y (ZnO) z (0≦x≦5, 0≦y≦5, 0≦z≦5), wherein: X or Z is greater than Y in the first region of the semiconductor layer, Y is greater than X and Z in the second region of the semiconductor layer, the first region of the semiconductor layer, in which X or Z is greater than Y, is a channel region which is a first distance from the gate electrode, the second region of the semiconductor layer, in which Y is greater than X and Z, is a back channel region which is a second distance from the gate electrode, the second distance being larger than the first distance, and at least one of X and Z is not zero in the second region of the semiconductor layer, and an amount of each of In, Zn and Ga in the first region of the semiconductor layer is different from an amount of each of In, Zn and Ga in the second region of the semiconductor layer.