Sol - Gel Prepared By Zno Varistor Film And Its Properties

ZnO varistors, a kind of semiconductor, have been widely utilized as transient high-voltage protector and surge arrestor. With the development of LSI (Large Scale Integrated circuit) and GSI (Very Large Scale Integrated circuit), ZnO film varistors, the representational low-voltage varistors, which are used in the computer , communication apparatus , railway signal , automobile industry , subminiature electric motor and various electron devices have aroused people paying close attention to. The demand of varistors which have higher nonlinear coefficient,lower nonlinear voltage and leakage current, is increasingly manifold. ZnO thin films have more advantage of reducing the components'thickness than ZnO ceramic, so ZnO thin films have the potential in empoldering lower power and lower nonlinear voltage varistors.Sol-Gel method can realize the material chemical composition precisely controlled, and can compose well-proportioned multicomponent gel, the technology does not require the expensive instrument, and be propitious to change ZnO thin films'capabilities.In this thesis, ZnO thin films were prepared by sol-gel method on the silicon substrates, and the influence of the process conditions on the crystallization and orientation of the films were studied for improving the process condition and optimizing the microstructure of ZnO thin films. The result indicates that the annealed temperature affects the microstructure and voltage-sensitive capacities of ZnO films mostly, 600℃is the best annealed temperature.In this thesis, we changed the adulteration concentration of Bi2O3,Co2O3 and Cr2O3 to carry out an optimization. The results indicate that when the three kinds additives adulteration concentration are all 0.5%, ZnO thin film varistors have the best voltage-sensitive capacities. The nonlinear voltage of the ZnO thin film varistors was 3.13V, nonlinear coefficient was 12.63, and leakage current was 25.34μA.Under the condition of appropriate adulterations, Bi2O3 can promote the formation of crystal boundaries when the films are annealed, Co2O3 can increase barrier potential altitude and improve the nonlinear coefficient, Cr2O3 can reduce the leakage current and improve the nonlinear coefficient.