A thin film transistor and its preparation method, an array substrate, a display

Embodiment of the present invention provides a thin film transistor and a method of preparation, an array substrate, a display, to display technology; while maintaining high on-state current of the thin film transistor of the thin film transistor to reduce leakage current, to ensure that the reliable thin film transistor performance. The thin film transistor includes: a gate, a gate insulating layer, an active layer, source and drain electrodes; wherein the active layer comprises a first layer of an active layer and a second active layer, and the second an active layer disposed adjacent to a side of the gate insulating layer, the second active layer disposed adjacent to the source and the drain side; the carrier mobility is greater than the first active layer said second carrier mobility in the active layer. Required for manufacturing the thin film transistor while keeping the thin film transistor of high on-state current reduce the leakage current of the thin film transistor, and the manufacturing the array substrate and the display includes the thin film transistor.