壓電效應是當施加應力於不對稱晶體結構之材料時，產生?負離子的錯移，形成 電極化的現象。氧化鋅為 n 型半導體材料，同時具有壓電特性，透過應變產生的壓電 勢(piezo-potential)來控制金屬與半導體接面的蕭特基能障(Schottky barrier)大小，稱為 壓電光電子效應(Piezotronics effect)，可應用於壓力感測器上。然而較低的壓電係數 (12.4 pC/N)以及應力靈敏度(Stress sensitivity)導致氧化鋅不利於?方向發展，本研究 利用釩(Vanadium)摻雜氧化鋅，以較小半徑的釩離子取代鋅的位置，增強電極化強度， 進而提升壓電係數。?外，釩摻雜也會導致晶粒尺寸、晶格缺陷、載子濃度及能帶結 構的改變，進而影響壓電光電子效應的性能。
本實驗使用氧化鋅(ZnO)以及五氧化二釩(V2O5)靶材進行射頻磁控共濺鍍技術， 藉由調控不同五氧化二釩靶材的濺鍍功率，以改變釩的摻雜濃度，並觀察釩摻雜氧化 鋅薄膜之表面形貌、壓電係數和能帶結構的變化，最後結合金電極，形成具有壓電光 電子效應的壓力感測器，透過施加不同重量之砝碼作為應力，探討其壓力靈敏度。
研究成果顯示:藉由釩的摻雜，使氧化鋅表面晶粒尺寸縮小，晶界以及表面缺陷 比例上升，進而導致載子濃度的減少。在合適的五氧化二釩靶材濺鍍功率下(40 W)， 釩摻雜氧化鋅維持 (002) c 軸取向，同時，以較小半徑之五價釩摻雜，強化了氧化鋅 的極化能力，壓電係數因而由 12.4 pm/V 提升至 24.3 pm/V。?外，本研究也成功製 備具有壓電光電子效應之壓力感測器，在相同負載下，釩摻雜氧化鋅的應力靈敏度由 100 MPa-1 上升至 250 MPa-1，經由能帶結構及載子傳輸分析可得知，釩摻雜降低了氧 化鋅的功函數(Work function)與電子親和力(Electron affinity)，形成了強蕭特基能障和 內電場強度(Build-in voltage)，再加上低載子濃度抑制了屏蔽效應(Screen effect)，避免 壓電勢被抵消，使得整體壓電壓力感測器之性能提升。

In this study, vanadium(V) doped zinc oxide(ZnO) thin film which deposited by RF magnetron co-sputtering system with ZnO and V2O5 targets were be observe the changes in surface morphology, lattice defects, piezoelectric coefficient, carrier concentration, and band structure. Finally, the V doped ZnO thin films were coated with gold electrodes to fabricate the piezoelectric pressure sensors, which operate based on the piezotronic effect, and their sensitivity was investigated. According to experimental results, under the appropriate doping power(40 W), the (002) c-axis orientation was maintained. Additionally, doping V5+ ions, which have smaller radius, enhanced the polarization of the V-O bonds, thereby increasing the piezoelectric coefficient from 12.4 pm/V to 24.3 pm/V. Furthermore, as the vanadium doping concentration increased, the grain size of ZnO on the surface decreased and the proportion of grain boundaries and surface defects increased, besides the carrier concentration decreased, which limited the screening effect by preventing the cancellation of the piezoelectric potential. Furthermore, vanadium doping reduced the work function and electron affinity of zinc oxide, forming a strong Schottky barrier and internal electric field intensity, thereby enhancing the overall performance of the piezoelectric pressure sensor with sensitivity and rectifier ability. The stress sensitivity could reach up to 1060 MPa-1.

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