Effect of the Grain Growth Process on the Characteristics for the Excimer Laser Crystallized Poly-Si Thin Film Transistors

We have found, for excimer laser crystallized poly-Si thin films, that there are two different grain growth processes that depend on the energy density. Columnar grains grow laterally at lower energy densities. The other grain growth process at higher energy densities is shown to be secondary grain growth caused by a less oriented structure with fine granular grains. A TFT with the maximum mobility is obtained at the border for the lower energy grain growth. Grain boundary and intragrain defects around grain boundary formed through the secondary grain growth reduce the mobility in spite of considerable grain enlargement.