Patent ID: 8300031

Claim:
A semiconductor device comprising: an electrode; a diode comprising: a first impurity region; and a second impurity region; a first transistor comprising: a first terminal connected to a first wire; a second terminal; and a gate terminal connected to a second wire; a second transistor comprising: a first terminal connected to a third wire; a second terminal directly connected to the electrode; and a gate terminal directly connected to the second terminal of the first transistor; and a third transistor comprising: a first terminal directly connected to the gate terminal of the second transistor; a second terminal connected to a fourth wire through the diode; and a gate terminal directly connected to the fourth wire, wherein the first impurity region is directly connected to the second terminal of the third transistor, wherein the second impurity region is directly connected to the fourth wire, wherein the first terminal of the third transistor, the second terminal of the third transistor, the first impurity region and the second impurity region are included in one island-shaped semiconductor layer, wherein the first terminal of the third transistor, the second terminal of the third transistor and the first impurity region comprise a first dopant, and wherein the second impurity region comprises a second dopant.