| 摘要 |
The present invention is to prevent the minus shift of a threshold voltage or an increase of the off current of a thin film transistor. In a thin film transistor (150), a buffer layer (106) is formed between a source electrode layer (107a), a drain electrode layer (107b) and an oxide semiconductor layer (103). A buffer layer (106) has a metal oxide layer (105) of insulator or semiconductor on the center part of the oxide semiconductor layer (103). The metal oxide layer (105) functions as a protection layer which prevents the penetration of impurity into the oxide semiconductor layer (103). Therefore, an increase of the off current of the thin film transistor (150) or the minus shift of a threshold value can be prevented. |
