Chemical solution deposited silver tantalate niobate, Agx(Ta0.5Nb0.5)O3-y, thin films on (111)Pt/Ti/SiO2/(100)Si substrates
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Silver tantalate niobate films are candidates for temperature stable microwave dielectrics. In this work, a chemical solution deposition synthesis method was developed for Ag (x)(Ta0.5Nb0.5)O3-y films on Pt-coated Si substrates. Stable solutions with a range of silver stoichiometries were prepared using 2-methoxyethanol and pyridine as solvents, from AgNO3 and Nb and Ta ethoxide precursors. It was extremely difficult to prepare phase-pure perovskite films of Ag(Ta0.5Nb0.5)O-3 on Pt-coated Si subtrates; instead a mixture of perovskite and natrotantite phases was identified. Such mixed phase films had dielectric constant epsilon(r) and dielectric loss tan delta values ranging from 200 +/- 20 to 270 +/- 25 and 0.006 +/- 0.002 to 0.002 +/- 0.001 at 100 kHz, respectively, depending on the firing temperature. For Ag-2(Ta0.5Nb0.5)(4)O-11, Ag-0.8(Ta0.5Nb0.5)O-2.9, Ag-0.85(Ta0.5Nb0.5)O-2.925 and Ag-0.9(Ta0.5Nb0.5)O-2.95 films, mainly the natrotantite phase was observed. The epsilon (r) values of these films were between 70 +/- 10 and 130 +/- 15 with tan delta values of 0.008 +/- 0.002 at 100 kHz.