The Dielectric Properties Of Barium Strontium Titanate Thin Films By Pulsed Laser Deposition

Due to the high dielectric constant and excellent dielectric nonlinearity, Ba1-xSrxTiO3 (BST)thin films have potential application in dynamic random storage, phase shifter, tunable microwave devices and so on. BST thin films based on Si substrate have been investigated extensively because of the compatibility with semiconductor technology. At present, the main problem of BST thin film is that the dielectric loss is difficult to meet the requirements for application, while the doping modification makes an effective way to solve the problem. In this paper,the Ba0.5Sr0.5TiO3 ceramics doped with different concentrations of Mn were prepared by solid state reaction method,which were used as target material for BST thin films by pulsed laser deposition(PLD). The preparation parameters of BST/LNO/Si by PLD were researched and Mn was used as dopant for the BST doping. The results are as followed:(1) The effects of sintering condition on the crystallinity and dielectric properties of Ba0.5Sr0.5TiO3 ceramics by solid-state reaction method were observed, the results determined the sintering temperature of 1300 ?. Then the dielectric properties of ceramic samples with different Mn doping concentration were investigated. It was found that the dielectric constant of Mn doped BST ceramics decreased with added dopant, but dielectric loss decreased firstly then increased.(2) The BST thin film were prepared on LNO/Si by PLD method, The effects of growth parameter such as oxygen pressure, laser energy and pulse rate on the microstructure of BST thin films was investigated, and high quality BST thin films were obtained under optimum parameters.(3) The influence of Mn doping concentration on the dielectric properties of BST thin films was studied. Compared to the ceramics, the dielectric properties of BST thin films showed a same varieties that the dielectric constant decrease with added dopants, and the dielectric loss decreases firstly then increased. In addition, Mn doping played an important role in improving the leakage current of BST thin films. The results showed that 2 mol% Mn doped BST thin film performed a better dielectric properties.