本研究聚焦於表面增強拉曼散射（Surface-enhanced Raman Scattering, SERS）技術於生物醫學感測的潛在應用。SERS 透過金屬與分子接觸界面所產生的局部電磁共振，可顯著放大拉曼訊號提升至十萬甚至百萬倍等級。SERS具備高度靈敏、良好分子識別能力與無須標記等特性。然而，SERS 偵測仰賴奈米尺度的電磁熱點，為提升訊號穩定性與熱點密度，我們採用有機金屬化學氣相沉積（Metal-Organic Chemical Vapor Deposition, MOCVD）技術，在藍寶石基板上製備InGaN/GaN量子井結構，藉此增加晶片表面的載子濃度，也提升SERS訊號的穩定度。
我們展示該氮化物SERS基材於循環腫瘤DNA（ctDNA）檢測的實際應用，並藉由調控磊晶層設計與量測條件，成功放大DNA目標序列的拉曼訊號強度，為無標記癌症早期診斷提供一種具發展潛力的策略。
實驗結果發現，調控銦通量並採用四層量子井結構，相較於三層量子井，可顯著提升拉曼增強效果。此外，針對不同濃度之DNA樣本進行SERS量測與分析，發現其拉曼光譜具有可辨識的差異，並在光學顯微鏡下觀察到濃度變化所導致的樣本分布行為，有機會應用在癌症的基因檢測。

This study explores the use of Surface-Enhanced Raman Scattering (SERS) for biomedical sensing, particularly for detecting circulating tumor deoxyribonucleic acid (ctDNA). SERS enhances Raman signals through localized electromagnetic resonance at the metal–molecule interface, achieving signal amplification up to 10⁵–10⁶ times. To improve signal stability and hotspot density, InGaN/GaN quantum well (QW) structures were grown on sapphire substrates using metal-organic chemical vapor deposition (MOCVD). These nitride-based structures increase surface carrier density and stabilize the SERS signals.
We applied the nitride SERS substrate to detect ctDNA and optimized the quantum well design and measurement conditions. Results show that using four QW layers and higher indium flux improves signal intensity compared to the three-QW structures. SERS spectra of DNA at different concentrations showed clear difference, and optical microscopy revealed changes in sample distribution. These findings indicate that the nitride SERS platform offers a sensitive and label-free method for ctDNA detection, showing potential in the genetic testing for cancer diagnosis.

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