Patent ID: 8581243

Claim:
A bottom gate type thin-film transistor comprising at least: a substrate, a gate electrode, a gate insulating layer, and a semiconductor layer in that order; a pair of a source electrode and a drain electrode, and said transistor having a lower interface between said gate electrode and said gate insulating layer and an upper interface between said gate insulating layer and said semiconductor layer, wherein said semiconductor layer is an In—Ga—Zn—O thin film which is an amorphous oxide semiconductor film and shows an electron mobility of not less than 2 cm 2 /Vs, wherein said lower interface has a difference between hill tops and dale bottoms of unevenness in a direction along a thickness of the gate insulating layer, of 30 nm or less, and wherein a difference between hill tops and dale bottoms of unevenness in said direction at said upper interface is not more than a layer thickness of said semiconductor layer, and wherein said layer thickness of said semiconductor layer is within a range of 15 nm or more to less than 45 nm.