隨著各種低耗電的便攜式逐漸普及在日常生活中，一個穩定且可以持續供電的能源便成一個重要的課題。奈米發電機是一個前景被看好可以解決微型電子裝置能源問題的電子元件，可以直接從環境中捕捉機械能並且將其轉換為可以運用的電能。近年來，奈米發電機已經有許多研究，元件製作的物理原理也逐漸被揭開，目前正朝著擴大應用的範圍發展。氧化鋅是一個Ⅱ-Ⅵ族的n型半導體材料，因為其同時具有壓電的特性，故其在壓電電子學上佔有一席之地。除此之外，氧化鋅具備優越的光學特性，因此又有壓電光子學方面的運用。
氧化鋅的壓電係數約為12.4pm/V，文獻中有許多方法能提升氧化鋅的壓電係數，像是研究新材料。以ZnSnO3為例，和氧化鋅相比可以提升12倍。或者是化學摻雜，化學摻雜又可以分成物理性質和化學性質，物理性質方面，像是鎂金屬摻雜;而化學性質方面，像是鋰金屬摻雜，在氧化鋅奈米線鍍上金奈米顆粒也可以提升壓電奈米發電機的輸出或利用氧化鋅奈米線的結構異向性也是有用的方法。
然而，這些方法有很多限制。本實驗根據之前本團隊以孔洞氧化鋅奈米線的研究成果，將其發展到奈米線之上。利用退火將射頻磁控濺鍍薄膜孔洞化，並運用不同的退火溫度製造不同大小和密度的孔洞氧化鋅薄膜，並以XRD觀察其結晶性和TEM觀察證明孔洞氧化鋅的產生乃是因為Zn原子和O原子向矽基板擴散的結果。並且藉由量測壓電係數(d33)了解在850℃下孔洞化的氧化鋅薄膜的確可以提升氧化鋅的壓電係數2.75倍，除了結晶性造成的提升外，孔洞附近的壓縮應力也是造成孔洞氧化鋅奈米發電提升的主因之一，證實孔洞可以有效改善壓電性質。
除此之外，為了擴充材料的應用性，我們將我們的材料製備成奈米發電機，觀察其開路電壓，和850℃下退火的試片和原始的氧化鋅相比，多了3倍的輸出，除了前述提到的壓電係數提升，薄膜機械性質的改善也是使輸出再提升的更高的一個重要因素。

Although piezoelectric semiconductors such as ZnO are considered as the promising candidates for piezotronics and piezoelectric nanogenerators (PENG), their piezoelectric coefficients are typically low. One of the strategies to enhancing piezoelectric properties proposed earlier by our group is to render nanorods porous. This idea is extended in this work, where porous ZnO thin films are first attempted by annealing RF-magnetron-sputtered ZnO films on Si substrate via kirkendall effect. Scanning electron microscopy images confirm the formation of aligned and faceted pores toward the bottom of the ZnO thin film. Through transmission electron microscopy (TEM) analysis, the pore formation mechanism is proposed to result from the out-diffusion of Zn and O atoms from ZnO to react with Si, causing the emergence of zinc silicate and silicon dioxide interfacial layers. High-resolution TEM images clearly reveal the lattices along the C axis nearby the pores experience compressive strain reducing from 0.5201nm to 0.4975nm, achieving the objectives of creating pores. Benefitted from the pores, the piezoelectric coefficient (d33) of the porous ZnO thin films determined by piezoelectric force microscopy can reach 2.64pm/V, which is 1.8 times higher than that of pristine ZnO thin films. Accordingly, compared to pristine ZnO, the PENG based on the porous ZnO thin film presents higher open-circuit voltage by up to 7.5 times. The enhancement is attributed to pore-induced higher d33, improvement of crystallinity and accompanying lower elastic modulus. Optimally, the introducing of pores has been confirmed to be beneficial to PENG of single-phase piezoelectric semiconductor thin films analogous to nanorods.

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