A T-shaped-gated (T-gate) poly-Si thin-film transistor (TFT) with symmetric vacuum gaps has been proposed and fabricated simply with a selective-etching technique and an in situ vacuum encapsulation. The proposed TFT has demonstrated a higher maximum on-off current ratio and superior reliability compared to the conventional TFTs. This is attributed to the resulting offset region and vacuum gap to reduce the off-state leakage current and improve the hot-carrier reliability, while the extra subgate serves to induce an inversion layer at the offset region to maintain the on current during the on state. Therefore, such a T-gate poly-Si TFT is very suitable for manufacturing and applications in active-matrix flat panel electronics. (c) 2006 The Electrochemical Society.