Semiconductor device, light-emitting device, and electronic device
An object is to prevent an operation defect and to reduce an influence of fluctuation in threshold voltage of a field-effect transistor. A field-effect transistor, a switch, and a capacitor are provided. The field-effect transistor includes a first gate and a second gate which overlap with each other with a channel formation region therebetween, and the threshold voltage of the field-effect transistor varies depending on the potential of the second gate. The switch has a function of determining whether electrical connection between one of a source and a drain of the field-effect transistor and the second gate of the field-effect transistor is established. The capacitor has a function of holding a voltage between the second gate of the field-effect transistor and the other of the source and the drain of the field-effect transistor.
1. A light-emitting device comprising:
a first transistor;
a second transistor;
a third transistor;
a first capacitor;
a second capacitor; and
a light-emitting element,
wherein the first transistor comprises a first gate electrode, a second gate electrode, and a semiconductor layer that comprises a channel formation region,
wherein the first transistor is capable of supplying current to the light-emitting element,
wherein the semiconductor layer comprises a region interposed between the first gate electrode and the second gate electrode,
wherein the first gate electrode is electrically connected to a data signal line through the second transistor,
wherein the first gate electrode is electrically connected to the first capacitor,
wherein the second gate electrode is electrically connected to a potential supply line through the third transistor, and
wherein the second gate electrode is electrically connected to the second capacitor.
2. The light-emitting device according to claim 1 , wherein the semiconductor layer is an oxide semiconductor layer.
3. The light-emitting device according to claim 2 ,
wherein the oxide semiconductor layer comprises regions whose c-axes are perpendicular to a surface of the oxide semiconductor layer, and
wherein a direction of a-axis of one of regions is different from a direction of a-axis of another of regions.
4. The light-emitting device according to claim 2 , wherein the oxide semiconductor layer comprises an In—Ga—Zn-based oxide.
5. The light-emitting device according to claim 1 , wherein a threshold voltage of the first transistor is capable of varying depending on a potential of the second gate electrode.
6. The light-emitting device according to claim 1 , wherein the light-emitting element is an electroluminescent element.
7. The light-emitting device according to claim 1 , further comprising:
a fourth transistor; and
a fifth transistor,
wherein the light-emitting element is electrically connected to a potential supply line through the fourth transistor, and
wherein the second gate electrode is electrically connected to a potential supply line through the fifth transistor.
8. A light-emitting device comprising:
a first transistor;
a second transistor;
a third transistor;
a first capacitor;
a second capacitor; and
a light-emitting element,
wherein the first transistor comprises a first gate electrode, a second gate electrode, and a semiconductor layer that comprises a channel formation region,
wherein the first transistor is capable of supplying current to the light-emitting element,
wherein the semiconductor layer comprises a region interposed between the first gate electrode and the second gate electrode,
wherein the first gate electrode is electrically connected to a data signal line through the second transistor,
wherein the first gate electrode is electrically connected to the first capacitor,
wherein the second gate electrode is electrically connected to a potential supply line through the third transistor,
wherein the second gate electrode is electrically connected to the second capacitor,
wherein the second gate electrode is directly connected to a first terminal of the second capacitor, and one of a source or drain of the first transistor is directly connected to a second terminal of the second capacitor.
9. The light-emitting device according to claim 8 , wherein the semiconductor layer is an oxide semiconductor layer.
10. The light-emitting device according to claim 9 ,
wherein the oxide semiconductor layer comprises regions whose c-axes are perpendicular to a surface of the oxide semiconductor layer, and
wherein a direction of a-axis of one of regions is different from a direction of a-axis of another of regions.
11. The light-emitting device according to claim 9 , wherein the oxide semiconductor layer comprises an In—Ga—Zn-based oxide.
12. The light-emitting device according to claim 8 , wherein a threshold voltage of the first transistor is capable of varying depending on a potential of the second gate electrode.
13. The light-emitting device according to claim 8 , wherein the light-emitting element is an electroluminescent element.
14. The light-emitting device according to claim 8 , further comprising:
a fourth transistor; and
a fifth transistor,
wherein the light-emitting element is electrically connected to a potential supply line through the fourth transistor, and
wherein the second gate electrode is electrically connected to a potential supply line through the fifth transistor.