Distributed phase shifters using (Ba,Sr)TiO3 thin films on sapphire and glass substrates |
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| Authors: | Yu Liu Baki Acikeia Amit S. Nagra Troy R. Taylor Peter J. Hansen James S. Speck |
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| Affiliation: | 1. Electrical and Computer Engineering Department , University of California at Santa Barbara , Santa Barbara, California, 93106;2. Materials Department , University of California at Santa Barbara , Santa Barbara, California, 93106 |
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| Abstract: | Abstract Sol-gel solutions were synthesized by using various alkoxides of polyhydric alcohol, carboxylate and stabilizer. Stability of modified sol-gel solution was good enough to keep its properties after at least three months although that of ordinary sol-gel solution is not good. SBT films were fabricated on Pt(200nm)/Ti(20nm)SiO2(500nm)/Si substrate at under 700°C by using modified sol-gel solution. Range of drying temperature was 200 to 400°C and that of RTA was 550 to 700°C. At high drying temperature, decrease of crystallinity for SBT films was observed accompanied by nucleation of Sr carbonate. On the other hand, SBT film dried at under 250°C and crystallized at 700°C shows high crystallinity of layer perovskite. SBT film derived from conventional sol-gel solution used to show strong crystal orientation of c-axis. In case of modified sol-gel solution, RTA temperature and amount of added stabilizer influenced crystal orientation of film. So it was possible that to control crystal orientation of SBT films by adjust RTA condition and amount of stabilizer. Stability of sol-gel solution and property of SBT films were influenced by component of solvent, electric properties of SBT films especially I-V property were improved. Using low temperature deposition process at 650°C, SBT films derived from modified sol-gel solution show superior ferroelectric properties to SBT thin films derived from conventional MOD solution. |
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| Keywords: | BaSrTiO3 ferroelectric varactor distributed phase shifter |
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