鋯鈦酸鉛梯度鐵電薄膜極化位移現象之Slater理論解釋

Applying Slater Model to Explain the Phenomenon of Polarization Displacement of PZT Graded Ferroelectric Films

10.6409/JMSE.200303.0046

張正義(C. Y. Chang)；雷健明(C. M. Lei)；曹佑民(Y. M. Tsau)；陳宜君(Y. C. Chen)；鄭秀鳳(H. F. Cheng)

梯度鐵電薄膜 ； 極化位移量 ； 有效焦電係數 ； graded ferroelectric thin films ； polarization offset ； effective pyroelectric coefficient

材料科學與工程

35卷1期（2003 / 03 / 01）

46 - 51

繁體中文

本論文主要是在討論脈衝雷射鍍膜法(PLD)所鍍製出的鋯鈦酸鉛(PZT)梯度鐵電薄膜之極化位移現象發生的條件，並以Slater理論解釋。比較兩種不同組成成份與退火溫度的鐵電薄膜，發現在外加電場不同的情況下，其極化位移量的大小各有不同，由此可證明極化位移現象的發生與薄膜組成成分及外加電場有關係。本實驗所得到的最重要的結果為證明了極化位移量與最大外加電場的2γ(1≤γ≤2)次方成正比，符合Slater理論的解釋，故可用Slater理論來解釋極化位移現象。又從改變溫度會發生極化位移現象的觀點來看，可證明極化位移現象的發生與溫度也有關係。此外，實驗結果顯示梯度鐵電薄膜的焦電係數比傳統焦電係數大了一個數量級，所以梯度鐵電薄膜比一般的鐵電薄膜更具有發展的潛力。

Graded ferroelectric devices (GFDs) showed the phenomenon of polarization displacement while increasing the applied electric field or temperature. The hysteresis loop of GFDs showed the asymmetric polarization displacement behavior with up or down direction that depended on the structure of graded composition. The PZT graded ferroelectric films were prepared from Pb (Zr(subscript x)Ti(subscript l-x))O3 target via using pulsed laser deposition technique. The polarization offset was proportional to 2γ(1≤γ≤2) power of maximum driving field, and this relation was corresponding to Slater model's prediction. When two different ratios of moles on zirconium and titanium of PZT graded ferroelectric films were compared, the results of experiment showed that the two ferroelectric films had different polarization offset while increasing electric field. The conditions of polarization displacement were affected by the graded composition, applied electric field, and temperature. The graded structure and composition were the necessary conditions for showing the polarization displacement behavior. Finally, we also discussed the difference between conventional and effective pyroelectric coefficients of the PZT graded ferroelectric films.