Patent ID: 8525182

Claim:
A display device comprising: a thin film transistor including: an insulating layer; a gate electrode provided on the insulating layer; a gate insulating film provided on the gate electrode; a semiconductor layer provided on the gate electrode, the semiconductor layer being formed of oxide; a source electrode and a drain electrode provided on the semiconductor layer, the source electrode being opposed to one end of the gate electrode, the drain electrode being opposed to another end of the gate electrode, the another end being opposite to the one end, the drain electrode being apart from the source electrode, a pixel electrode connected to one of the source electrode and the drain electrode, the pixel electrode being formed of the oxide and having a lower electric resistance than the semiconductor layer; an optical element producing at least one of a change in optical characteristics and light emitting by an electric signal provided to the pixel electrode; and a film provided under the pixel electrode and formed of the same material as the gate insulating film, a surface of the gate insulating film on a side of the semiconductor layer being smoother than a surface of the film on a side of the pixel electrode.