Twin-grain Si thin-film transistors produced by single-shot irradiation of excimer-laser light

A new Si thin-film transistor (TFT) has been proposed where only one grain boundary exists midway between the source and drain. The proposed device was fabricated by a novel excimer-laser crystallization method, and the device characteristics were evaluated. The article shows schematics of the proposed TFT having the unique feature that there is only one grain boundary in the channel. Since the source and drain are in their own grains with good crystallinity, leakage current of the TFT under off-conditions is expected to be as low as that of MOST in ULSIs. Since a potential barrier formed at the boundary is low for an excimer-laser-annealed poly-Si film and number of grain boundaries is only one, the on-current is expected to be as high as that of MOST. Deep traps at the grain boundary can act effectively as a carrier recombination center, and they can potentially kill the undesirable kink effect.