| 摘要 |
In a thin film transistor, an increase in off-state current or a negative shift of a threshold voltage is prevented. The thin film transistor (150) provides a buffer layer (106) between an oxide semiconductor layer (103) and each of a source electrode layer (107a) and a drain electrode layer (107b). The buffer layer (106) includes a metal oxide layer (105) which is an insulator or a semiconductor over the center part of the oxide semiconductor layer (103). The metal oxide layer (105) functions as a protective layer for suppressing the penetration of impurities into the oxide semiconductor layer (103). Therefore, in the thin film transistor, the increase in off-state current or the negative shift of the threshold voltage can be prevented. |
