Source follower circuit or bootstrap circuit, driver circuit comprising such circuit, and display device comprising such driver circuit

A semiconductor device comprising:

• a buffer circuit comprising a source follower circuit, comprising:
• a first n-channel transistor;
• a second transistor;
• a third transistor;
• and
• a capacitor,
• wherein:
• a first terminal of the first n-channel transistor is electrically connected to a first terminal of the second transistor,
• a second terminal of the first n-channel transistor is electrically connected to a power source,
• a second terminal of the second transistor is electrically connected to a ground,
• a first terminal of the third transistor is electrically connected to a gate electrode of the first n-channel transistor,
• the capacitor is connected to the first terminal of the first n-channel transistor, a first terminal of the second transistor, and the first terminal of the third transistor, and
• channel forming regions of the first n-channel transistor and the second transistor comprise a semiconductor film.

A semiconductor device comprising:

• a buffer circuit comprising a source follower circuit, comprising:
• a first n-channel transistor;
• a second n-channel transistor;
• a third transistor;
• and
• a capacitor,
• wherein:
• a first terminal of the first n-channel transistor is electrically connected to a first terminal of the second n-channel transistor,
• a second terminal of the first n-channel transistor is electrically connected to a power source,
• a second terminal of the second n-channel transistor is electrically connected to a ground,
• a first terminal of the third transistor is electrically connected to a gate electrode of the first n-channel transistor,
• the capacitor is connected to the first terminal of the first n-channel transistor, a first terminal of the second transistor, and the first terminal of the third transistor, and
• channel forming regions of the first n-channel transistor and the second n-channel transistor comprise a semiconductor film.