二氧化鋯與二氧化鉿奈米雙層薄膜之鐵電性研究

二氧化鉿陶瓷系統薄膜在從2011年開始的研究中被認為具有鐵電性，因此被視為是一種嶄新且有潛力的無鉛鐵電材料。從最開始含有元素摻雜的二氧化鉿系統、二氧化鋯-二氧化鉿陶瓷固溶體系統，直到最近的不含摻雜元素的純二氧化鉿系統，都已經有文獻指出鐵電性的存在。一般而言，二氧化鉿具有三個結晶相，分別為單斜晶相、正方晶相和立方晶相；這三個二氧化鉿結晶相皆為中心對稱，因此從結晶學上此三種結晶相皆不可能為鐵電性的來源。因此，文獻中指出，應是另一種非中心對稱的斜方晶相造成二氧化鉿擁有鐵電性。此種斜方晶相的生成是來自於所使用的氮化鈦電極對於氧化物薄膜的限制所造成的影響，因此有一系列的文章持續的對二氧化鉿陶瓷系統薄膜做更進一步的開發。然而，根據參考的二氧化鋯相圖，此種結晶相必須在高溫且一定的壓力下才能穩定存在；因此，對於二氧化鉿陶瓷薄膜實際形成斜方晶相的機制尚不完備。本研究中試著結合X光繞射儀、電子顯微鏡、鐵電分析儀、以及元素分析的結果，試著去解釋二氧化鉿、二氧化鋯以及其雙層堆疊薄膜系統的鐵電表現，提出鐵電性來源可能機制，期望使二氧化鉿及二氧化鋯薄膜的鐵電表現在未來能夠有系統地做進一步的研究以及發展。

關鍵字

二氧化鉿；二氧化鋯；鐵電性；雙層薄膜； TEM

並列摘要

Recently, HfO2-based system was reported to have ferroelectricity. Doped-HfO2, binary Hf1-xZrxO2 and undoped-HfO2 film on TiN electrode have ferroelectricity in particular experimental condition. The high-pressure orthorhombic phase having noncntrosymmetric Pbc21 space group, which is induced by encapsulation of TiN electrode, has been claimed as the origin of ferroelectricity in HfO2. Although simple application based on ferroelectric HfO2-based system has been made, the mechanism forming ferroelectric HfO2 is not fully understood. In the present study, ferroelectric characteristics of ZrO2, HfO2, and bilayer ZrO2/HfO2 film fabricated by ALD on Pt/Ti/SiO2/Si substrate has been measured and determined in this study. The mechanism by which ZrO2 and HfO2 form a ferroelectric phase and the factors influencing the phase transition are explained by combining the results of structural information, characteristic hysteresis loop, chemical analysis and phase diagram. With knowing the mechanism forming ferroelectric HfO2 and antiferroelectric ZrO2, it is believed that the two material systems have potential to be used as new lead-free ferroelectric material in near future.

並列關鍵字

Hafnia ； Zirconia ； Ferroelectricity ； Bilayer thin films ； TEM

參考文獻

1. Wang, J., Li, H. P. & Stevens, R. Hafnia and hafnia-toughened ceramics. J. Mater. Sci. 27, 5397–5430 (1992).

2. Hannink, R. H. J., Kelly, P. M. & Muddle, B. C. Transformation toughening in zirconia-containing ceramics. J. Am. Ceram. Soc. 83, 461–487 (2000).

3. Robertson, J. High dielectric constant gate oxides for metal oxide Si transistors. Rep. Prog. Phys. 69, 327 (2006).

4. Graeve, O. A. in Ceramic and Glass Materials 169–197 (Springer, 2008).

5. Ho, S.-M. On the structural chemistry of zirconium oxide. Mater. Sci. Eng. 54, 23–29 (1982).

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二氧化鋯與二氧化鉿奈米雙層薄膜之鐵電性研究

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