The correlation between composition and preferred orientation of ferroelectric SrBi2Ta2O9 thin films

The composition and preferred orientation of the ferroelectric SrBi2Ta2O9 ( SBT) films deposited by a modified radio-frequency (rf) magnetron sputterin g technique were investigated as a function of the bismuth and tantalum spu ttering powers. The increase of bismuth in SBT films induces the growth of c axis orientation and the decrease of Bi induces the growth with (115) pre ferred orientation. The optimum peak intensity ratios of (008) to (115) pla ne showing the highest remanent polarization of SBT films were about 2.408. The 250 nm thick Sr0.8Bi3.4Ta2.0O9 films deposited under the optimum condi tions of rf power of 100 W, Bi dc power of 25 W, and Ta dc power of 10 W sh owed a remanent polarization, P-r, of 7.51 mu C/cm(2), and a coercive field , E-c, of 28 kV/cm at an excitation voltage of 5 V. The SBT films showed pr actically no polarization fatigue after 7.0 x 10(10) switching cycles. (C) 1999 The Electrochemical Society. S1099-0062(98)07-022-9. All rights reserv ed.