| abstract |
An object of the present invention is to provide a transistor having an oxide semiconductor layer with stable electrical characteristics. Further, an object of the present invention is to provide a highly reliable semiconductor device having a transistor. The semiconductor device includes a multilayer film including an oxide layer and an oxide semiconductor layer, a gate insulating film provided in contact with the oxide layer, and a gate electrode provided to overlap the multilayer film via the gate insulating film, wherein the oxide The layer contains the same element as the oxide semiconductor layer and has a larger energy gap than the oxide semiconductor layer, and the composition between the oxide layer and the oxide semiconductor layer continuously changes. |