The authors report on the influence of Mg acceptor doping on the markedly reduced leakage current characteristics (< 5x10(-8) A/cm(2) at 2 MV/cm) of Ba0.6Sr0.4TiO3 thin films. The suitability of room temperature deposited Mg-doped Ba0.6Sr0.4TiO3 films as gate insulators for low-voltage ZnO thin-film transistors (TFTs) (< 6 V) was investigated. All room temperature processed ZnO-TFTs on plastic substrates exhibited a high field-effect mobility of 16.3 cm(2)/V s and a current on/off ratio of 6.4x10(4). The threshold voltage and subthreshold swing were 2.8 V and 400 mV/decade, respectively. (c) 2007 American Institute of Physics.