Sc2O3 doped Bi2O3-ZnO thin films varistor prepared by sol-gel method

Sc2O3 modified Bi2O3-ZnO films varistors with different doping ratios were prepared by Sol-gel method. The result indicated that doping of Sc2O3 significantly enhance the nonlinear current-voltage (I-V) characteristics of Bi2O3-ZnO films. The highest non-linearity was obtained for 0.4mol% Sc content with the nonlinear coefficient α = 3.7 and 301 μA in leakage current. The grain size of ZnO phase firstly increased with Sc2O3 doping when the content of Sc2O3 is no more than 0.2 mol%. Upon the much more doping of Sc2O3, the growth of ZnO crystal was inhibited, leading to smaller grain size. The threshold voltage VT was inversely proportional with grain size of ZnO phase. Doping oxides gathered in the grain boundary significant impact on threshold voltage and leakage current.