SiC/AlN上外延GaN薄膜的黄带发光与晶体缺陷的关系

利用室温光致发光(PL)技术研究了在6HSiC(0001)上用金属有机物化学汽相沉积(MOCVD)外延生长的GaN薄膜“黄带”发光(YL)特点,与扫描电子显微镜(SEM)、X射线衍射(XRD)技术得到的GaN薄膜的表面形貌质量和内部结晶质量的结果相对照,表明“YL”发光强度与GaN薄膜的扩展缺陷多少直接相对应通过二次离子质谱(SIMS)技术获取的GaN薄膜中Ga元素深度分布揭示出镓空位(V_Ga)最可能是“YL”发光的微观来源分析认为,虽然宏观扩展缺陷(丝状缺陷、螺形位错等)和微观点缺陷V_Ga及其与杂质的络合物(complexes)都表现出与“YL”发射密切相关,但V_Ga及其与杂质的络合物更可能是“YL”发射的根本微观来源室温下获得的样品“YL”发射强度和光谱精细结构可用于分析GaN薄膜缺陷和晶体质量.

The Relation of Yellow Band Luminescence of Undoped GaN Epitaxial Grown on AlN/6H-SiC(0001) Substrate with Thin Film Defects

The Yellow-band luminescence (YL) from undoped GaN epilayers grown on SiC substrate with a buffer layer AlN using metal organic chemical vapor deposition (MOCVD) has been observed and studied .Comparing with GaN thin films crystallization quality and surface morphological results from X-ray diffraction and scanning electron microscopy (SEM), respectively,It is found the YL emission (luminescence) intensity can fully characterize the qualities of GaN epilayers. The deep profiles of Ga atom in GaN epilayers obtained by Secondary ion mass spectrometry (SIMS) technique showed that a absence of Ga be present in GaN near the interface of between GaN epilayer and AlN buffer, which strongly implied VGa and its complexes with impurities(O N) are likely responsible for the YL emission. Although extended defects (twist dislocations,threading dislocations ,stacks, grain boundaries et al)originated from substrate are strongly relevant to YL emissions. the V Ga and its complexes are likely the microstructures that bring YL emissions.