Patent ID: 8415667

Claim:
A semiconductor device comprising a transistor, the transistor comprising: an oxide semiconductor layer; a gate electrode layer adjacent to the oxide semiconductor layer; a gate insulating layer interposed between the oxide semiconductor layer and the gate electrode layer; and a source electrode layer in contact with the oxide semiconductor layer and a drain electrode layer in contact with the oxide semiconductor layer, wherein a work function (φ m ) of a conductor used for the source electrode layer and the drain electrode layer satisfies φ m >χ+E g /2, wherein a barrier for holes (φ Bp ) represented by (χ+E g −φ m ) is less than 0.25 eV, and wherein an electron affinity of an oxide semiconductor used for the oxide semiconductor layer is represented by χ (eV) and a band gap of the oxide semiconductor used for the oxide semiconductor layer is represented by E g (eV).