| Recently, the fabrication of thin films of functional ceramics has received more and more attention as a result of miniaturization and high integration. The huge current such as voltage surges always lead to various serious problems, such as erroneous working and the destruction of electronic devices. Therefore, the development of thin film with varistor characteristic is quite significant for protecting the devices. Strontium titanate(SrTiO3) is a kind of ceramic with good varistor character. And it is also has excellent capacitive character. As a result, it can not only protect the devices from voltage surge, but also can eliminate noise. Therefore, it is very necessary to fabricate strontium titanate based double-function thin film. The process of SrTiO3 films were focused on.SrTiO3 thin film was prepared by sol-gel process. Several decisive factors were studied by changing one factor at one time, including mole ratio of H2O and Ti, volume ratio of H2O and HAC, the amount of ethanol absolute, et al. after investigation and analysis of the samples by XRD, the growing parameters were optimized. Good quality SrTiO3 thin film was obtained: 40:1(molH2O:molTi), 1.4:1(VH2O:VHAc), 10ml(ethanol absolute), 850℃ (annealing temperature), 1hour(aging time).The impact of dopant concentration was studied. And the effecting mechanism of donor dopant(La3+) and acceptor dopant(Mn2+) were analyzed respectively. The experiment results demonstrated that the semiconducting and insulating process were influenced by the donor dopant(La3+) and acceptor dopant(Mn2+). Double function SrTiO3 thin films with varistor voltage V1mA=27.6V · mm-1;nonlinear coefficient α = 2.8;relative dielectric constant εr=120;dielectric loss tan 6 =0.08 was obtained: 1.0% donor dopant(La3+), 1.0% acceptor dopant(Mn2+). |
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