Embodiments disclosed herein generally relate to TFTs and methods of fabricating the TFTs. In TFTs, the active channel carries the current between the source and drain electrodes. By tailoring the composition of the active channel, the current can be controlled. The active channel may be divided into three layers, a gate control layer, a bulk layer, and an interface control layer. The separate layers may have different compositions. Each of the gate control, bulk and interface control layers may additionally comprise multiple layers that may have different compositions. The composition of the various layers of the active channel comprise oxygen, nitrogen, and one or more elements selected from the group consisting of zinc, indium, cadmium, tin, gallium and combinations thereof. By varying the composition among the layers, the mobility, carrier concentration and conductivity of the various layers may be controlled to produce a TFT having desired properties.