Thin film transistor, array substrate and display device having the same, and method of manufacturing thereof

A thin film transistor comprising an active layer comprising a metal oxynitride, a source electrode, and a drain electrode;

• wherein the active layer is partially covered by an etching stop layer on top of the active layer;
• the active layer has a first region contacting the etching stop layer, a second region contacting the source electrode, and a third region contacting the drain electrode;
• and
• the first region has an oxygen content lower than that of at least one of the second region and the third region.