在現今的世界中，科技日新月異，帶動了所有的相關產業。其中，生醫也成為了一種新興且快速成長的研究領域，為了維持優良的生活品質，生醫方面的相關知識也成了最炙手可熱的研究議題。表面增強拉曼散射(surface-enhanced Raman scattering, SERS)是一種檢測快速、靈敏度高又穩定，還具有再現特性，是一種極具潛力的生醫感測工具。在本研究中，為了改善SERS訊號的有效面積及穩定度，我們利用有機金屬化學氣相沉積法(metal organicchemical vapor deposition, MOCVD)成長氮化物SERS晶片。 我們以藍寶石基板，先將設定溫度在550 ℃，成長微米尺度的氮化鎵成核(nucleation)結構，再將溫度拉高至 1120 ℃，成長單晶氮化鎵，接著通入氫氣，藉由氫氣本身具有蝕刻效果的特性，使氫氣滯留反應艙內數秒至數分鐘，使氮化鎵表面變得粗糙且均勻，最後在磊晶多層量子井以提高樣品表面電荷密度。完成後，我們利用掃描式電子顯微鏡觀察SERS晶片的表面結構，並以rhodamine 6G (R6G)當作待測物分子來觀察拉曼訊號。根據量測果，我們發現氫氣的蝕刻效應及MOCVD的腔體壓力與SERS的訊號強度有密切的關係。;Surface-enhanced Raman scattering (SERS) is a biosensing technique with the advantages of high speed and high sensitivity. The technique has drawn tremendous research efforts in the last two decades.
In this study, we use metal organic chemical vapor deposition (MOCVD) to grow nanostructured InGaN SERS substrates, with the attempt to improve the scalability and reproducibility of SERS signals.
The MOCVD growth started with a GaN nucleation layer at 550 ℃ on the sapphire substrate. The substrate temperature was then increased to 1120 ℃ for the growth of high-quality GaN epitaxial layer. After that, hydrogen gas was introduced to the reactor, within which a roughened surface morphology of GaN was formed for the SERS structure. Finally, we grew InGaN/GaN multiple quantum wells (MQW) to increase electron on the surface. Scanning electron microscopy (SEM) was employed to observe the surface of the SERS samples and rhodamine 6G (R6G) was used as the analyte to evaluate the SERS intensity. It is found that the etching effect of H2 gas and reactor pressure of MOCVD play important roles in SERS effect on the nanostructure MQW.
