A Low-cost Materials Processing Solution for Achieving Low Insertion Loss, Affordable Tunable Devices for Next Generation On-The-Move Communications Systems-Part II

Report No. ARL-TR-5227
Authors: M. W. Cole, E. Ngo, R. Tan, R. C. Toonen, S. G. Hirsch, M. Ivill, C. Hubbard, and T. Anthony
Date/Pages: June 2010; 32 pages
Abstract: We report on the development of an innovative post-growth/crystallization isothermal ultraviolet (UV)-photon irradiation process science protocol, which improves the quality factor and leakage characteristics of complex multi-component dielectric films while sustaining high dielectric tunability. We developed two experimental approaches and down-selected the best in class process to achieve enhanced and balanced material properties, i.e., minimizing dielectric loss without degrading dielectric tunability. Specifically, we fabricated Ba1-xSrxTiO3, (BST) thin films using a combinational processing technique, which blended metalorganic solution deposition (MOSD) film growth and UV-photon irradiation isothermal treatment via two process science protocols: (1) MOSD in situ crystallized isothermal UV-photon irradiation processed films, referred to as the "Single Step Anneal" and (2) MOSD post-crystallization isothermal UV-photon irradiation processed film, referred to as the "Two-Step Anneal" process. Our research supports the following scientific claims: (1) Isothermal UV-photon irradiation treatment improves the structural quality of the BST films; (2) BST films exposed to isothermal UV-photon irradiation processing for 225 min resulted in lattice parameters approaching that of bulk values, evidence for a reduction in oxygen vacancy point defect concentration; and, (3) MOSD fabricated BST films crystallized via conventionally furnace annealing (CFA) at 700 ¿C/60 min, and subsequently exposed to isothermal UV-proton irradiation for 225 min possessed improved structural, dielectric, and electrical quality compared to traditional CFA films and in situ isothermal UV-photon irradiation processed BST films. The results suggest that low loss, highly tunable films with excellent leakage characteristics are achieved via applying isothermal UV-photon irradiation processing to fully crystallized MOSD fabricated BST films. This research introduced non-complex, affordable processing routes for fabricating tunable, active thin-film oxides that satisfies the requirements for the balanced competing material properties of low dielectric loss and high tunability.
Distribution: Approved for public release
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Last Update / Reviewed: June 1, 2010