The embodiments described herein generally relate to methods for forming a multi-layer amorphous silicon structure that may be used in thin film transistor devices. In one embodiment, a method includes positioning a substrate comprising a buffer layer in a process chamber, the process chamber comprising a processing region, forming a plurality of amorphous silicon layers and annealing the amorphous silicon layers to form a polycrystalline silicon layer. Forming the plurality of layers includes delivering a silicon-containing precursor and a first activation gas to the processing region to deposit a first amorphous silicon layer over the buffer layer, the silicon-containing precursor and the first activation gas being activated by a plasma and maintaining a continuous flow of the silicon-containing precursor while delivering a second activation gas, without the first activation gas, to the processing region to deposit a second silicon layer on the first silicon layer.