Chemical solution deposited silver tantalate niobate, Ag _x (Ta_0.5Nb_0.5)O_3-y , thin films on (111)Pt/Ti/SiO₂/(100)Si substrates

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 (Ta_0.5Nb_0.5) O_3-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(Ta _0.5Nb_0.5)O₃ on Pt-coated Si subtrates; instead a mixture of perovskite and natrotantite phases was identified. Such mixed phase films had dielectric constant _r and dielectric loss tanδ values ranging from 200±20 to 270±25 and 0.006±0.002 to 0.002±0.001 at 100kHz, respectively, depending on the firing temperature. For Ag₂(Ta_0.5Nb_0.5)₄O₁₁, Ag_0.8(Ta_0.5Nb_0.5)O_2.9, Ag _0.85(Ta_0.5Nb_0.5)O_2.925 and Ag _0.9(Ta_0.5Nb_0.5)O_2.95 films, mainly the natrotantite phase was observed. The _r values of these films were between 70±10 and 130±15 with tan δ values of 0.008±0.002 at 100 kHz.