In this work, high-performance polycrystalline Si thin film transistors have been fabricated by excimer laser crystallization of an amorphous Si film deposited on an array of amorphous Si spacers. The amorphous Si spacers served as seeds for lateral growth during excimer laser irradiation. Large longitudinal grains could be found in the device channel regions. In consequence, the thin-film transistors fabricated with Si spacer structure exhibited a high field-effect mobility of 288 cm(2)/V-s while the mobility of the conventional counterpart was 129 cm(2)/V-s. In addition, the uniformity of the device performance was improved as lateral growth could be artificially controlled. (C) 2004 The Electrochemical Society.