Embodiments of the present invention disclose a
thin film transistor, a method of manufacturing a
thin film transistor, an array substrate and a
display device, which may ensure
electrical connection between source and drain electrodes and an
active layer without configuring any through hole due to providing an etch stop layer between the
active layer and the source and drain electrodes, a portion of the etch stop layer being in contact with the source and drain
electrode is made of
metal or
metal alloy; and may ensure insulation between the source and the drain electrodes when the
thin film transistor is turned-off, ensuring normal operation of the thin film
transistor, by oxidating the portion of the etch stop layer at the position between the source and the drain electrodes as an insulating material. The etch stop layer may not only prevent the
active layer from being damaged when
etching the source and drain electrodes, but also prevent the active layer from other adverse effects from subsequent processes, such as adverse effects from water,
hydrogen and
oxygen, etc., thereby enhancing performance of the thin film
transistor, just because of providing the etch stop layer between the active layer and the source and drain electrodes in the thin film
transistor.