Thin film transistor and display device including the same

A thin film transistor comprising:

• a first gate electrode on a substrate;
• a gate insulating film on the first gate electrode;
• a first active layer on the gate insulating film;
• a drain electrode on one side of the first active layer;
• a first source electrode on another side of the first active layer;
• a second active layer on the drain electrode;
• a second source electrode on the second active layer:
• a sidewall spacer on sidewalls of the drain electrode, the second active layer, and the second source electrode;
• and
• a second gate electrode on a sidewall of the sidewall spacer.

A display device comprising:

• a scan line extending in a first direction;
• a data line extending in a second direction crossing the first direction;
• and
• a thin film transistor provided at a point at which the data line and the scan line cross each other,
• wherein the thin film transistor comprises:
• a first gate electrode on a lower substrate;
• a gate insulating film on the first gate electrode;
• a first active layer on the gate insulating film;
• a drain electrode on one side of the first active layer;
• a sidewall spacer on a sidewall of the drain electrode;
• and
• a first source electrode provided on another side of the first active layer and a sidewall of the sidewall spacer.