Characterization of Novel Polycrystalline Silicon Thin-Film Transistors with Long and Narrow Grains

Excellent characteristics of polycrystalline silicon (poly-Si) thin-film transistors (TFTs) with long and narrow grains aligned one-dimension have been experimentally clarified for the first time. The field effect mobility and on-off transition slope of n-channel and p-channel devices were as high as 685 cm 2 V -1 s -1 and 190 mV/decade and 145 cm 2 V -1 s -1 and 104 mV/decade, respectively. Fluctuations of characteristics were considerably reduced by widening the channel, and uniform characteristics were observed when there were approximately twenty long grains within the channel. These results were obtained when the TFT channel was formed within a region free from grain boundaries formed by head-on collision of laterally growing grains and seeds used to initiate lateral grain growth. Material properties are discussed from the viewpoint of device characteristics.