Abstract: A thin film transistor includes at least an oxide semiconductor layer, a gate insulating film, a gate electrode, a source-drain electrode, and a protective film in this order on a substrate and further includes a protective layer. The oxide semiconductor layer includes an oxide constituted of In, Ga, Zn, Sn, and O. The atomic ratio of each metal element in the oxide semiconductor layer satisfies the following relationships: 0.09?Sn/(In+Ga+Zn+Sn)?0.25, 0.15?In/(In+Ga+Zn+Sn)?0.40, 0.07?Ga/(In+Ga+Zn+Sn)?0.20, and 0.35?Zn/(In+Ga+Zn+Sn)?0.55. The protective layer contains SiNx. The thin film transistor has a mobility of 15 cm2/Vs or more.

Abstract: Disclosed herein is a thin film transistor including at least an oxide semiconductor layer, a gate insulting film, a gate electrode, a source-drain electrode and a protective film in this order on a substrate and further including a protective layer. The oxide semiconductor layer includes an oxide constituted of In, Ga, Sn and O and an atomic ratio of each metal element satisfies the following relationships: 0.30?In/(In+Ga+Sn)?0.50, 0.19?Ga/(In+Ga+Sn)?0.30 and 0.24?Sn/(In+Ga+Sn)?0.45. The protective layer contains SiNx, and mobility is 35 cm2/Vs or more.