Protrusions of Super Grains Formed by Ultrashort Xe Flash-Lamp Annealing of Amorphous Silicon and Its Effect on the Performances of Thin-Film Transistors

We studied the formation of super grains and protrusions at the grain boundaries by the ultrashort Xe flash-lamp annealing of amorphous silicon. Huge protrusions at the grain boundary originate from the collision of nearby super grains with an average grain diameter of 40 mu m, and small protrusions at the grain boundary are also observed. The crystallization starts from the seeds located at the center of the grains by releasing heat toward the surrounding Si. The formation of grain boundaries is related to lateral grain growth and pushing liquid silicon toward the direction of grain growth and the collisions between them. Thin-film transistors (TFTs) with various grain boundaries in the channel were investigated, and the p-channel poly-Si TFTs with two and four grain boundaries exhibited the maximum field-effect mobility of 112 and 75 cm(2)/V . s, respectively.