氮化鋁鎵表面缺陷之光性和原子力顯微鏡影像特性研究

Abstract

在本論文中，我們利用原子力顯微鏡(AFM)，掃描電位顯微鏡(SKM)以及微米光激發光譜(micro-PL)等方法，研究氮化鋁鎵薄膜的表面缺陷。其中原子力顯微鏡掃描出六角形的凹洞結構，其寬度大約為1μm，深度為300nm，剖面圖為V字形，為一般所通稱之V-defect。藉掃描電位顯微鏡，發現在凹洞中的表面電位比周圍平坦區域的表面電位低了約0.2V，推測是在凹洞區域產生了類受子形式的缺陷能帶。最後再利用微米光激發光譜量測六角形凹洞處的光譜，發現在凹洞處多了與缺陷相關的譜峰，其發光能量比近能隙發光能量低了0.1eV，我們認為此一譜峰為凹洞所導致的缺陷能帶所產生。

The optical and AFM image characteristics of AlGaN surface defects were characterized by atomic force microscopy (AFM), scanning Kelvin microscopy (SKM) and micro-photoluminescence (micro-PL). The AFM image of the surface defects shows an open hexagonal inverted pyramid on the (0001) plane, the so-called “V-defect”, with walls formed by {10-11} planes. The depth of the V-defect is about 300nm and the width is about 1μm. The SKM image revealed that the surface potential of the V-defect is ~0.2V lower than that of the flat region. We suggested that there are acceptor like defect band in the V-defect. The micro–PL revealed that there are extra peak in the V-defect, which energy is 0.1eV lower than the NBE energy. We suggested the origin of the extra peak is the defect band induced by V-defect.