以迴旋濺鍍法於藍寶石基板低溫成長氮化鋁薄膜之特性研究

Characterization of Low Temperature Grown AlN Films on Sapphires Using Helicon Sputtering Method

10.7049/JCYU.201207.0001

陳美汝(Meei-Ru Chen)；高慧玲(Hui-Ling Kao)

氮化鋁 ； 低溫沉積 ； 穿透率 ； 光學能隙 ； 迴旋濺鍍系統 ； AlN ； low temperature growth ； transmittance ； optical band gap ； helicon sputtering system

清雲學報

32卷3期（2012 / 07 / 01）

1 - 11

繁體中文

本論文利用迴旋濺鍍系統，於低溫下直接在藍寶石基板沉積氮化鋁薄膜，以X光繞射檢測此薄膜為c軸從優取向，並以φ方向掃描驗證為磊晶薄膜；薄膜之表面粗糙度則使用原子力顯微鏡觀測及估算，其表面粗糙度的均方根值僅為0.6-1.3 nm。此外，從穿透率量測中發現氮化鋁薄膜於可見光波段具有極高的穿透率（大於80%），且於波長200 nm處有明顯吸收現象，再利用吸收係數計算法而得到此材料之最佳光學能隙為6.13 eV；更進一步利用陰極螢光量測觀察到其能隙邊緣躍遷為6.32 eV，皆與6.2 eV的能隙理論值很接近。此研究結果證實利用迴旋濺鍍系統，即使在晶格不匹配度高達12%的藍寶石基板上，仍可成功於低溫下成長高品質之氮化鋁磊晶薄膜，並可將其應用於表面聲波元件及紫外光波段之光學領域。

AlN thin films have been deposited directly on sapphire substrates at low temperatures by a helicon sputtering system in this study. The structural quality of AlN epitaxial films was confirmed by X-ray diffractometry and the surface morphology of AlN films with root-mean-square roughness of 0.6-1.3 nm was observed and evaluated by an atomic force microscope. In addition, the AlN epilayers exhibit an optimal band gap of 6.13 eV and a high transmittance of over 80% in the visible range. The near band edge transition of AlN was also obtained to be 6.32 eV from the cathodoluminescence measurement. The results of this low temperature deposition suggest the possibility of direct epitaxial growth of AlN on sapphire substrates and demonstrate the feasibility of incorporating AlN films for the surface acoustic wave devices and the optical applications in the ultraviolet region.