A two-layer oxide comprised of SiO2 and Al2O3 grown at 150degreesC by atomic layer deposition (ALD) was investigated as the gate insulator for ultralow temperature poly-Si thin-film transistors (ULTPS TFTs). The two-layer gate insulator satisfied good interface quality and low leakage current at the same time. Using this material, n-channel ULTPS TFTs were fabricated on poly-Si with a threshold voltage of 2.3 V and a field-effect mobility of 104 cm(2)/V s without hydrogenation. (C) 2004 The Electrochemical Society.