Patent ID: 8779478

Claim:
A thin film transistor provided on a substrate, comprising: a gate electrode; a gate insulating film covering the gate electrode; a semiconductor layer placed to face the gate electrode with the gate insulating film interposed therebetween; a source electrode connected to the semiconductor layer; and a drain electrode separated from the source electrode and connected to the semiconductor layer, wherein the semiconductor layer is comprised of a metal oxide semiconductor including an oxide of at least one of In, Ga, or Zn, and has a source portion that contacts the source electrode, a drain portion that contacts the drain electrode, and a channel portion that is located between the source and drain portions, a reduced region is formed at least in the channel portion of the semiconductor layer, and the reduced region has a higher content of a simple substance of In than a remaining portion of the semiconductor layer, the reduced region extends substantially in the entire channel portion, the metal oxide semiconductor includes an oxide of In, and the reduced region is a region of the semiconductor layer where an amount of oxygen included in the semiconductor layer has been reduced by a reduction process.