Display device and electronic device

Abstract

An object is, in a structure where switch circuits in a signal line driver circuit is placed over the same substrate as a pixel portion, to reduce the size of transistors in the switch circuits and to reduce load in the circuits during charging and discharging of signal lines due to the supply of data. A display device is provided which includes a pixel portion receiving a video signal, and a signal line driver circuit including a switch circuit portion configured to control output of the video signal to the pixel portion. The switch circuit portion includes a transistor over an insulating substrate. The transistor has a field-effect mobility of at least 80 cm 2 /Vs or more. The transistor includes an oxide semiconductor layer.

1 . (canceled) 
     
     
         2 . A display device comprising:
 a pixel portion; and   a signal line driver circuit configured to drive the pixel portion, the signal line driver circuit comprising a switch circuit portion,   wherein the switch circuit portion comprises a transistor,   wherein the transistor has a field-effect mobility of 80 cm 2 /Vs or more, and   wherein the transistor comprises an oxide semiconductor layer comprising In, Sn, and Zn.   
     
     
         3 . The display device according to  claim 2 , wherein the transistor has the field-effect mobility of 120 cm 2 /Vs or more. 
     
     
         4 . The display device according to  claim 2 ,
 wherein the transistor further comprises:
 a source electrode and a drain electrode which are electrically connected to the oxide semiconductor layer; 
 a gate electrode; and 
 a gate insulating film between the oxide semiconductor layer and the gate electrode. 
   
     
     
         5 . The display device according to  claim 2 , wherein a concentration of hydrogen in the oxide semiconductor layer is lower than 5×10 19  cm −3 . 
     
     
         6 . The display device according to  claim 2 ,
 wherein a concentration of sodium in the oxide semiconductor layer is lower than 5×10 16  cm −3 ,   wherein a concentration of lithium in the oxide semiconductor layer is lower than 5×10 15  cm −3 , and   wherein a concentration of potassium in the oxide semiconductor layer is lower than 5×10 15  cm −3 .   
     
     
         7 . A display device comprising:
 a pixel portion; and   a signal line driver circuit configured to drive the pixel portion, the signal line driver circuit comprising a switch circuit portion,   wherein the switch circuit portion comprises at least a first transistor, a second transistor, and a third transistor,   wherein each of the first transistor, the second transistor, and the third transistor has a field-effect mobility of 80 cm 2 /Vs or more,   wherein each of the first transistor, the second transistor, and the third transistor comprises an oxide semiconductor layer comprising In, Sn, and Zn,   wherein a gate of the first transistor is electrically connected to a sampling signal output circuit through a first wiring,   wherein a gate of the second transistor is electrically connected to the sampling signal output circuit through a second wiring,   wherein a gate of the third transistor is electrically connected to the sampling signal output circuit through a third wiring,   wherein one of a source and a drain of the first transistor is electrically connected to a first pixel through a fourth wiring,   wherein one of a source and a drain of the second transistor is electrically connected to a second pixel through a fifth wiring,   wherein one of a source and a drain of the third transistor is electrically connected to a third pixel through a sixth wiring, and   wherein the other of the source and the drain of the first transistor, the other of the source and the drain of the second transistor, and the other of the source and the drain of the third transistor are electrically connected to a video signal output circuit through a seventh wiring.   
     
     
         8 . The display device according to  claim 7 , wherein each of the first transistor, the second transistor, and the third transistor has the field-effect mobility of 120 cm 2 /Vs or more. 
     
     
         9 . The display device according to  claim 7 ,
 wherein each of the first transistor, the second transistor, and the third transistor further comprises:
 a source electrode and a drain electrode which are electrically connected to the oxide semiconductor layer; 
 a gate electrode; and 
 a gate insulating film between the oxide semiconductor layer and the gate electrode. 
   
     
     
         10 . The display device according to  claim 7 , wherein a concentration of hydrogen in the oxide semiconductor layer is lower than 5×10 19  cm −3 . 
     
     
         11 . The display device according to  claim 7 ,
 wherein a concentration of sodium in the oxide semiconductor layer is lower than 5×10 16  cm −3 ,   wherein a concentration of lithium in the oxide semiconductor layer is lower than 5×10 15  cm −3 , and   wherein a concentration of potassium in the oxide semiconductor layer is lower than 5×10 15  cm −3 .