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Media Used ferroelectric phase shift Performance Optimization

Author: WangBo
Tutor: YangChuanRen
School: University of Electronic Science and Technology
Course: Electronic information materials and components
Keywords: Ferroelectric thin films RF magnetron sputtering BST BZT Nonlinear
CLC: TN623
Type: Master's thesis
Year: 2008
Downloads: 123
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Abstract


Used as the medium phase ferroelectric thin film material, must have a large dielectric constant, linear strength, dielectric loss (tgδ) small, low leakage current characteristic. Based on the annealing temperature, the preferred orientation, composition gradient research on barium strontium titanate (BST) thin film is optimized for performance. By RF magnetron sputtering method, successfully prepared barium zirconate titanate (BZT) thin films and studied the oxygen-argon ratio and Zr / Ti ratio for BZT thin films. Finally, BST, BZT films were reliability testing. Achieved the following results: 1. On different substrates of the BST thin film prepared to withstand the maximum annealing at different temperatures were 900 ℃ (Al 2 O 3 substrate), 1100 ℃ (LaAlO < sub> 3 substrate), and 1200 ℃ (MgO substrate). The substrate lattice constant and thermal expansion coefficient of the main factors affecting withstand temperatures. The higher the annealing temperature, BST films better bias characteristics, preferably higher values. 2. (110) preferred orientation of the BST thin film ferroelectric stronger than the (100) direction of merit, BST (110) has a larger dielectric constant film and the tuning rate, smaller tgδ. 3. BST films having a composition gradient having a lower dielectric loss, but a single layer structure as the tuning rate. Ba 0.5 Sr 0.5 TiO 3 / Ba 0.6 Sr 0.4 TiO 3 structure outperforms Ba 0.6 Sr 0.4 TiO 3 / Ba < sub> 0.5 Sr 0.5 TiO 3 structure. 4. By RF magnetron sputtering method, successfully prepared BZT polycrystalline films. BZT film well crystallized, smooth and dense, non-porous, uniform grain size, has low leakage current. Ferroelectric thin film is weak, the bias electric field of 400kV/cm, the tuning rate of 15%, tgδ is 0.016. Thickness halved after (bias electric field is 800kV/cm) tuning rate increased to 33.5%, tgδ 0.021 5. With the deposition O 2 / Ar ratio increases, BZT thin film orientation by the (l00) direction gradually to the (111) direction. The mean grain size, surface roughness, the dielectric constant, the tuning rate and tgδ all with O 2 / Ar ratio increases. BZT ferroelectric thin film is also enhanced. 6. Contrast BaZr 0.2 Ti 0.8 O 3 Films and BaZr 0.1 Ti 0.9 O 3 thin films and found to reduce Zr 4 content, BZT thin film ferroelectric, dielectric constant and tuning rates are bigger, especially tuned rate increased to 60.5% (bias electric field is 800kV/cm). 7. At -30 ℃ ~ 130 ℃ range, BST and BZT thin dielectric constant increases slowly with increasing temperature, did not show the Curie point. -50 ℃ ~ 150 ℃, 1MHz lower, BST and BZT film has better temperature stability. Also found that the BST and BZT thin film bias characteristics with good fatigue resistance.

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CLC: > Industrial Technology > Radio electronics, telecommunications technology > Electronic components, assemblies > Microwave transmission control components > Phase shifter, ferrite phase shifter
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