We investigated the effects of laser annealing on ZnO thin film transistors (TFTs). ZnO layers were deposited on a bottom-gate patterned Si substrate by radio-frequency sputtering at room temperature Laser annealing of the ZnO films reduced the full width at half maximum of the ZnO (002) diffraction peak from 0 49 degrees to 0.1 degrees. It reveals that the crystalline quality is improved by annealing effect A SiO(2) formed in low temperature was used as the gate dielectric Unannealed ZnO-TFTs were operated in enhancement mode with a threshold voltage of 21 6 V They had a field-effect mobility of 0 004 cm(2)/Vs and an on/off current ratio of 134 Laser annealing of the ZnO-TFTs by 200 laser pulses reduced their threshold voltage to 0 6 V and increased their field-effect mobility to 5 08 cm(2)/Vs The increase of mobility is originated from the crystallization enhancement of ZnO films after laser annealing (C) 2009 Elsevier B V All rights reserved