本研究利用溶膠凝膠法搭配旋轉塗佈法製備非晶態La2Ti2O7(LTO)薄膜，並透過電子束蒸鍍法沉積Al與Ti上電極，探討金屬-絕緣體-金屬(MIM)結構之電阻式記憶體(RRAM)元件的雙極電阻轉換行為，並討論不同薄膜厚度、不同上電極、不同薄膜退火溫度以及金屬後退火製程對於電阻轉換(RS)特性之影響。厚度約35.7 nm之一層薄膜元件擁有最佳的RS特性表現，隨著厚度上升元件之操作電壓增加而操作次數減少。在Al上電極與Ti上電極的比較中，Al上電極元件展現出較低的操作電壓與較多之循環次數，推測是上下電極之間的功函數差導致。退火處理元件之元件耐久度皆明顯下滑，透過XPS分析得知為退火後之氧空缺含量大幅下降所導致，也因此瞭解到由氧空缺主導元件的RS特性。最後利用金屬後退火製程成功在上電極界面處形成約9.52 nm厚之氧化鋁層，並使得薄膜內部氧空缺含量提升，獲得3671次之循環次數，電阻比(Ron/Roff)約101能夠分辨高低阻態，由上電極擴散至薄膜內的Al離子則幫助元件維持2.02 V/-1.30 V之低工作電壓，且於常溫及85℃下之記憶保留時間(Retention time)皆能夠達到一萬秒。本研究中所有以Al作為上電極之元件皆由相同之傳導機制主導，於Set過程之高阻態(HRS)為trap-controlled SCLC傳導機制，低阻態(LRS)為歐姆導通機制，Reset過程中之HRS與LRS則皆由歐姆導通機制主導。

Amorphous La2Ti2O7 (LTO) thin films were prepared by sol-gel method and the bipolar resistive switching (BRS) properties in metal (Al or Ti) /LTO/ITO devices were investigated. The influences of film thickness, top electrode, annealing temperature and post metal annealing (PMA) treatment on the resistive switching (RS) characteristics were also discussed. The single layer LTO thin film exhibits a better combination of RS performance because it is easy to form conductive filaments. Moreover, the work function difference between the top and the bottom electrode affects the RS performance of the devices. The RS characteristics of the devices are dominated by oxygen vacancies and the content of oxygen vacancies was seriously reduced after annealing, which led to a significant decrease of the endurance. In addition, PMA treatment increased the content of oxygen vacancies because of the formation of AlOx interface layer and made Al ions diffuse into the films, which improved the RS performance. The optimized RS characteristics of PMA 300℃ device shows 3671 switching cycles with a Ron/Roff ratio of 101, low operating voltage (VSet/VReset=2.02 V/−1.30 V) and over 104 seconds of retention time at room temperature and 85ºC, indicating the potential for practical RRAM applications. Conduction mechanism of all devices with Al top electrode were described by trap-controlled space-charge limited current (SCLC) and ohmic conduction.

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