本實驗以射頻濺鍍法生長以W取代Bi4-XLaXTi3O12（BLT）中Ti位置的BLTW薄膜並改變La與W的含量，其組成為Bi3.2La0.54Ti2.97W0.03（BL0.54TW0.03）、Bi3.2La0.73Ti2.97W0.03（BL0.73TW0.03）、Bi3.2La0.73Ti2.99W0.01（BL0.73TW0.01）、Bi3.2La0.73Ti2.95W0.05（BL0.73TW0.05）及Bi3.2La0.73Ti2.9W0.1（BL0.73TW0.1）共五種。並探討BLTW薄膜不同組成（La與W）、不同退火溫度（675至700℃）、不同退火氣氛（空氣、氧氣與氮氣）對其鐵電性質、漏電流及疲勞（fatigue）現象之影響。大多數BLTW薄膜於剛退火後遲滯曲線多少都有不飽和的現象。隨著時效時間經過，遲滯曲線漸漸飽和且殘留極化（2Pr）與矯頑力（2Ec）逐漸降至一定值。造成Pr隨時間遞減的機制可能為電荷缺陷擴散至晶格平衡位置、鬆弛效應與電荷缺陷釘住（pinning）晶域壁使其不易轉向的效應。與空氣中退火相比較，在氧氣與氮氣中退火將影響BLTW的結晶性較差，並且於氧氣中退火更會生成Bi2Ti2O7順電相，兩種情況皆會影響BLTW整體鐵電性質。殘餘極化（2Pr）值有隨著W含量自0增至0.03先增加而超過0.03則再隨之遞減的趨勢，這代表了BLT薄膜中添加W將對2Pr值造成兩種相反的效應（1）減少氧缺陷數量（2）降低晶格扭曲程度，隨著W增加後者影響越顯著。在漏電流的量測中，相同的電場（200kV/cm）下BLTW（10-7A/cm2）都較BLT（10-6A/cm2）薄膜低一個數量級。BLTW薄膜在較大的外加電場下進行疲勞測試可產生無疲勞（fatigue-free）的現象，這應該是field-assisted domain unpinning的效應所造成。取代元素含量增加（La與W取代Bi與Ti）也可改善BLTW薄膜的疲勞性質。二次退火（鍍Pt上電極之前先進行BLTW薄膜退火，之後再進行Pt/BLTW/Pt接觸退火）的試片所量測的各項鐵電性質均與一次退火（鍍完Pt上電極後再將Pt/BLTW/Pt進行退火，此時薄膜與接觸退火係同時完成）的試片大同小異，故一次退火應可成為簡化鐵電材料製程的一種方式。

The room temperature aging behavior, ferroelectricity, fatigue behavior, and leakage current of W-doped Bi4-XLaXTi3O12(BLTW) films with various La and W concentrations such as Bi3.2La0.54Ti2.97W0.03(BL0.54TW0.03), Bi3.2La0.73Ti2.97W0.03(BL0.73TW0.03), Bi3.2La0.73Ti2.99W0.01(BL0.73TW0.01), Bi3.2La0.73Ti2.95W0.05(BL0.73TW0.05), and Bi3.2La0.73Ti2.9W0.1(BL0.73TW0.1), which were deposited by radio-frequency(RF) sputtering and then annealed at a temperature of 675-750oC in air ,O2 and N2, respectively, were studied. Most of the polarization-electric field (P-E) loops of BLTW capacitors measured immediately after annealing showed somewhat leaky. Upon aging at room temperature the P-E loops could become saturated and thereafter the remanent polarization (Pr) and coercive field (Ec) decreased slowly with time and approached to a constant value. The mechanisms responsible for the decay of Pr with time may be the diffusion of charged defects to the equilibrium lattice sites, relaxation effect, and the domain pinning effect of charged defects. As compared with annealing in air, both annealing in O2 and N2 resulted in poor crystallization of BLTW films, furthermore, annealing in O2 could enhance the formation of pyrochlore Bi2Ti2O7 and thus degraded the ferroelectricity of the capacitors. The 2Pr increased with W concentration up to 0.03 and then dropped, indicating that adding W into the BLT films can induce two contrary effects on Pr, i.e., reducing the amount of oxygen vacancies and causing less structure distortion. With increasing the W concentration the latter effect gradually became dominant. The leakage current of BLTW capacitors is in the order 10-7 A/cm2 at the field of 200 kV/cm, being at least an order of magnitude lower than that of BLT capacitors. The BLTW capacitors showed fatigue-free at elevated cycling field, indicating that the fatigue-free behavior of BLTW capacitors is due to the field-assisted domain unpinning effect. The substitution of La and W for Bi and Ti respectively could improve the fatigue properties of BLTW capacitors. The ferroelectricity of the samples subjected to two-step annealing, viz., before deposition of top Pt electrodes the BLTW films are first annealed and then the contact annealing is performed on Pt/BLTW/Pt capacitors, is similar to that of the samples subjected to one-step annealing, viz., after deposition of top Pt electrodes the Pt/BLTW/Pt capacitors are annealed to simultaneously complete film and contact annealing.

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