| abstract |
In a thin film transistor using an oxide semiconductor, one of the problems is to improve the field effect mobility. Further, even if the field effect mobility of the thin film transistor is improved, it is one of the problems to suppress an increase in the off current. In a thin film transistor using an oxide semiconductor layer, the electric field effect mobility of the thin film transistor is improved by forming a semiconductor layer having a higher conductivity than the oxide semiconductor layer and a thin film thickness between the oxide semiconductor layer and the gate insulating layer. In addition, an increase in the off current can be suppressed. |