NOISE PERFORMANCES IN POLYCRYSTALLINE SILICON THIN-FILM TRANSISTORS FABRICATED BY EXCIMER-LASER CRYSTALLIZATION

A systematic study of the noise performances of polycrystalline silico n (polysilicon) thin-film transistors (TFTs) made by excimer laser cry stallization is presented. The drain current spectral density of these devices shows an evident 1/f behavior and the origin of the noise was attributed to carrier number fluctuations. The flat-band voltage spec tral density was found to be strongly correlated with the field-effect mobility, suggesting that the microscopic mechanism causing the carri er number fluctuations involves the localized states present at the gr ain boundaries. The noise level in the devices with the best electrica l characteristics is comparable with that observed in c-Si metal-oxide -semiconductor field effect transistors, a major improvement if compar ed to polysilicon TFTs made by solid-phase crystallization. (C) 1997 A merican Institute of Physics.