Roles of Target Composition on the Dielectric Property of RF Sputtered Bi 2 O 3 -ZnO-Nb 2 O 5 Pyrochlore Thin Film

Bi2O3-ZnO-Nb2O5 (BZN) thin films were well formed on a Pt/TiO2/SiO2/Si substrate by RF magnetron sputtering. Process induced nonstoichiometric of BZN yielded two typical crystalline structures i.e. cubic and monoclinic. Due to the low sputtering yield of Bi, BZN cubic phase, could be obtained not only from the sputtering of corresponding target (Bi1.5Zn0.5)(Zn0.5Nb1.5) O7 but also from the target which has Bi-enriched monoclinic composition (Bi2(Zn0.33Nb0.66)2O7). Even film which is deposited from monoclinic BZN has better tunability. It was observed that BZN cubic films were continuously deposited until target composition increased up to (Bi:Zn:Nb = 4.0:1:2) from stoichiometry (Bi:Zn:Nb = 3:1:2) and that tunability maximized with a dielectric constant of 184, loss tangent of 0.008, and maximum tunability of 42% at 1.1MV/cm from 3.2:1:2 composition. In the mid nonstoichiometric range, only Bi5Nb3O15 secondary orthorhombic phases were observed along with cubic phase which showed synergetic effects on BZN cubic films.