氧化鋅摻鈷成長於透明可撓式白雲母基板之薄膜性質研究

Abstract

為了追求自旋電子元件在應用上的更多可能性，本論文我們以脈衝式雷射系統在透明且具可彎曲性的白雲母基板上製備了過渡金屬摻雜半導體之一的氧化鋅摻鈷薄膜。經由一系列在結構、光學、電性，以及撓性上的研究，結果顯示出在與這種獨特基板的結合，氧化鋅摻鈷薄膜具備了卓越的物理性質。 藉由X射線繞射分析儀所進行的結構分析，顯示出氧化鋅摻鈷成長於雲母基板的製備上有很好的凡德瓦異質磊晶關係。並且，在原子力顯微鏡與穿透式電子顯微鏡的圖像裡，描繪出了樣品的形貌與表面粗糙度，以及在原子尺度之下的晶格排列。光學分析部分，透過紫外光-可見光光譜儀，樣品展現出大約80%的高透光度。令人驚奇地，成長於白雲母基板的氧化鋅摻鈷薄膜具有其他常見半導體所不具有之寬波長範圍的高透光(350奈米~2500奈米)。 除此之外，這個系統在電性量測的結果中也展現出它的半導體行為、室溫鐵磁性，以及在低溫時大約25%的磁阻。另外，氧化鋅摻鈷薄膜不僅僅具有以上提到的優異特性，經過一系列的撓性測試，得到了在彎曲狀態的光學、電性、與磁性行為，也表現出其機械靈活度和透明可撓自旋電子元件所必須具備的耐久性。

In order to search for broader possibilities of the application in spintronic devices, Co-doped ZnO (ZCO) thin films were grown on transparent and flexible muscovite (mica) via PLD process. Through a series of structural, optical, and transport studies, the results show that ZCO thin films possess remarkable physical properties under the combination with this kind of unique substrate. In the structure analysis by X-ray diffraction (XRD), a successful fabrication of ZCO/mica by van der Waals heteroepitaxy was demonstrated. Also, surface roughness, surface morphologies and lattice arrangement in the atomic scale were characterized by atomic force microscopy (AFM) and transmission electron microscope (TEM). High transmittance of about 80% in visible region of samples was revealed in the optical analysis from ultraviolet-visible (UV-Vis) transmittance measurements. Surprisingly, unlike other common semiconductors, ZCO/mica has wide transparency window (350 nm-2500 nm). The transport properties shows a semiconducting behavior, ferromagnetism at room temperature, and a high magnetoresistance of about 25 % at low temperatures. In addition to the unique properties mentioned above, we have also measured its optical, transport and magnetic properties in the bending state of the films. After a series of flexibility test, ZCO/mica thin films exhibit excellent mechanical flexibility and durability necessary for flexible transparent spintronic devices.