Properties of Ba(Mg1/3Ta2/3)O-3 thin films prepared by metalorganic solution deposition technique for microwave applications
Joshi, Pooran C.
Desu, Seshu B.
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We report on the properties of Ba(Mg1/3Ta2/3)O-3 thin films prepared by the metalorganic solution deposition technique. Bulk Ba(Mg1/3Ta2/3)O-3 ceramics have shown excellent dielectric properties at microwave frequencies; however, the high sintering temperature of bulk material is the major obstacle in their use as dielectric resonators to miniaturize microwave circuits. It was possible to obtain an ordered-perovskitz phase of 0.3-mu m-thick Ba(Mg1/3Ta2/3)O-3 films with trigonal symmetry at an annealing temperature of 700 degrees C, which is much lower than the bulk sintering temperatures. The electrical measurements were conducted on Pt/Ba(Mg1/3Ta2/3)O-3/Pt capacitors. The typical measured small signal dielectric constant and dissipation factor at 100 kHz were 22.2 and 0.009, respectively. The dielectric constant of thin films was comparable to the typical values (epsilon(r) similar to 23.5-25) reported for bulk ceramics. The temperature coefficient of capacitance was -145 ppm/degrees C in the measured temperature range of 25-125 degrees C. The leakage current density was lower than 10(-7) A/cm(2) at an applied electric field of 0.5 MV/cm. The high dielectric constant, which is comparable to bulk, low dielectric loss, and good temperature and bias stability suggest the suitability of Ba(Mg1/3Ta2/3)O-3 thin films for microwave communications and integrated capacitor applications. (C) 1998 American Institute of Physics. [S0003-6951(98)01931-7].