A ZnO thin-film transistor (TFT) with an MgO insulator was fabricated on a silicon (100) substrate using a radiofrequency magnetron sputtering system. The MgO insulator was deposited using the same deposition system; the total pressure during the deposition process was maintained at 5 mTorr, and the oxygen percentage of O-2/(Ar + O-2) was set at 30%, 50%, or 70%. The process temperature was maintained at below 300 degrees C. The dielectric constant of the MgO thin layer was approximately 11.35 with an oxygen percentage of 70%. This ZnO TFT displayed enhanced transistor properties, with a field-effect mobility of 0.0235 cm(2) V-1 s(-1), an I-ON/I-OFF ratio of similar to 10(5), and an SS value of 1.18 V decade(-1); these properties were superior to those measured for the MgO insulators synthesized using oxygen percentages of 30% and 50%. (C) 2014 Elsevier B.V. All rights reserved.