In accordance with some embodiments of the disclosed subject matter, a TFT, a related TFT array substrate, fabricating methods thereof, a display panel and a display device containing the same are provided. A method for fabricating a TFT is provided, the method comprising: forming an initial conductive layer on a base substrate; performing an oxidization process to partially oxidize the initial conductive layer to form an oxidized insulating sub-layer and a non-oxidized conductive sub-layer; and forming an active layer, a source electrode and a drain electrode over the oxidized insulating sub-layer.