Thin-film transistor (TFT) devices with either a top or a bottom sub-gate were fabricated and characterized. The top sub-gate scheme allows the self-aligned formation of main-gate with respect to the sub-gate. On the other hand, the bottom sub-gate scheme features a self-aligned field-induced drain with a sidewall spacer located on its top to set the effective field-induction-drain (FID) length. Unlike the conventional TFTs, the FID serves to distribute the high drain electric field and thereby eliminates gate-induced drain leakage-like off-state leakage current. Superior device performance is realized with the bottom sub-gate structure. (C) 2002 Elsevier Science Ltd. All rights reserved.