An L-shaped dual-gate device structure, which reduces kink current in polycrystalline silicon thin-film transistors (poly-Si TFTs), has been proposed and fabricated. In the proposed device, the poly-Si TFTs have a lateral grain growth in channels such as TFTs fabricated by sequential lateral solidification (SLS) or CW laser crystallization. The current flow of dual TFTs is strongly affected by grain boundaries showing lateral grain growth. The L-shaped dual gate structure is employed for asymmetry between dual channels. One of the channels is located in a parallel direction of grain growth and the other is located vertically. It is verified by experiment that the proposed L-shaped dual-gate TFT reduced the kink current of poly-Si TFT and showed improved reliability by fixed current flow in the saturation mode.