A new bottom-gated poly-Si thin-film transistor

We have proposed and fabricated the new bottom-gated poly-Si TFT with a partial amorphous-Si (a-Si) region by employing the selective laser annealing. The channel layer of the proposed TFTs is composed of poly-Si region in the center and a-Si region in the edge. The TEM image shows that the local a-Si region is successfully fabricated by the effective cut out of the incident laser light in the upper a-Si layer. Our experimental results show that the reverse leakage currents are decreased significantly in the new poly-Si TFT compared with conventional one. This reduction is due to the suppression of field emission currents by local a-Si region like that of a-Si TFTs while the ON currents are kept almost the same due to the considerable inducement of electron carriers in the short a-Si channel by the positive gate bias.