氧化鋅(Zinc oxide, ZnO) 是一種n型半導體材料，擁有直接且寬的能隙(3.3 eV)、高發光效率以及顯著的c軸(c-axis)優選成長方向，此外，氧化鋅亦有壓電及壓光電等效應，因此適合用於奈米發電機、發光二極體、紫外光感測器等光電元件。近幾年來，可攜帶型的電子產品趨向輕巧、智慧型以及多元化等方向推陳出新，使得電能的生產和儲存及其相關領域也漸漸受到重視。然而，傳統的發電方式，例如：火力發電、核能發電，皆有廢料處理、環境汙染等問題，同時它們皆也不利於攜帶型裝置的供電，因此研究可發電又兼具環保的材料是目前學術以及企業相當著重的議題，其中又以奈米發電機為目前最有潛力的元件之一。
本實驗利用合金化系統材料來試著提升氧化鋅的壓電係數(12.4 pm/V)，利用鎂原子置換氧化鋅中的鋅原子以改變原先材料的結構、鍵結、能隙及壓電係數等性質，其中，鎂摻雜進氧化鋅中可以大範圍地調控氧化鋅的能隙(3.3~7.3 eV)，因此氧化鋅鎂材料用來作為紫外光感測器也相當合適。本實驗以純氧化鋅及氧化鎂靶材共濺鍍出氧化鋅鎂系統之薄膜，在固定基板溫度、沉積氣體種類、沉積氣體流量等參數下探討不同含量的鎂元素摻雜對於氧化鋅的結構、能隙等特性的影響，並找出具有最佳壓電係數(d33)的氧化鋅鎂薄膜。結集所有合金化的材料特性後，就能研發及衍伸出具有多種功能之壓電元件、裝置。根據實驗結果顯示，大部分的氧化鋅鎂薄膜皆有明顯地柱狀結構並且有著以c軸成長的優選方向，隨著鎂含量上升，薄膜的柱狀結構漸漸地不明顯同時產生立方結構的相(cubic structure)。整體而言，氧化鋅鎂材料相較於純氧化鋅有明顯增加，但不會隨鎂含量上升而上升，約在鎂含量為11 at%之薄膜具有最高的壓電係數(~54 pm/V)，約為純氧化鋅之d33的4倍之多，證明合金化的確是提升壓電係數的方法之一。此材料可以結合半導體、壓電電子(piezotronic)、壓電光電子(piezo-phototronic)特性與壓電性(piezoelectricity)來提升元件的性質。最後，本研究還將製備的氧化鋅鎂薄膜用於壓電型奈米發電機元件，證明該材料確實可以做為奈米發電機的新壓電材料。
此實驗中還選用了有較高壓電係數的氧化鋅鎂薄膜，將其製備成簡易的奈米發電機元件，並與純氧化鋅元件做比較，結果顯示在不同頻率下的輸出電壓與電流密度，氧化鋅鎂薄膜元件皆具有較優異的輸出表現，證實氧化鋅鎂材料在壓電型奈米發電機元件具相當的潛力。在薄膜與元件皆未做任何的前處理或進一步的優化(optimized)的前提下，2.0赫茲的氧化鋅鎂薄膜就有高達0.1 V以及70 nA/cm2的電壓與電流密度輸出量，由此可見，若將元件改良或將薄膜做前處理，皆有很大的機會可以再提升這樣的輸出結果。

Wurtzite structure materials such as ZnO exhibits piezoelectric and semiconducting propertie, represented by piezoelectric coefficient as a dominant physical characteristic. In this paper, we investigate the dependence of piezoelectric coefficient on Mg content in MgxZn1-xO thin films deposited on Si (111) by radio frequency magnetron sputtering. The deposition temperature is fixed at 250℃ and all the films were grown to 380±20 nm in thickness. X-ray diffraction analysis confirms that all MgxZn1-xO films show high crystallinity with strong preferential orientation along [0001] growth direction. Moreover, the diffraction peaks shift toward higher angles, which confirms the substitution of the smaller ionic radius of magnesium for zinc sites. The morphology and composition of the films are examined by scanning electron microscopy and energy dispersive X-ray spectroscopy. The piezoelectric coefficient of MgxZn1-xO films are measured by piezoresponse force microscopy, exhibiting the maximum occurring at an intermediate Mg concentration, which is largely improved as compared to ZnO. And the MgxZn1-xO–based nanogenerators(NGs) also has better output performance than pure ZnO film-based NGs, which indicates that the MgxZn1-xO films hold great promise to be applied in piezoelectric NGs.

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