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Si衬底与GaN之间较大的晶格失配和热失配引起的张应力使GaN外延层极易产生裂纹,如何补偿GaN所受到的张应力是进行Si基GaN外延生长面临的首要问题。采用金属有机化合物化学气相沉积(MOCVD)技术在4英寸(1英寸=2.54 cm)Si(111)衬底上制备了GaN外延材料并研究了不同AlGaN缓冲层结构对Si基GaN外延材料性能的影响,并采用高分辨X射线衍射仪(HRXRD)、原子力显微镜(AFM)、喇曼光谱以及光学显微镜对制备的GaN材料的性能进行了表征。采用3层AlGaN缓冲层结构制备了表面光亮、无裂纹的GaN外延材料,其(002)晶面半高宽为428 arcsec,表面粗糙度为0.194 nm。结果表明,采用3层AlGaN缓冲层结构可以有效地降低GaN材料的张应力和位错密度,进而遏制表面裂纹的出现,提高晶体质量。
The main problem of epitaxial growth of Si-based GaN is how to compensate the tensile stress caused by GaN when the tensile stress caused by the larger lattice mismatch and thermal mismatch between the Si substrate and GaN mismatches the GaN epitaxial layer . GaN epitaxial materials were prepared on a 4 inch (1 inch = 2.54 cm) Si (111) substrate by metalorganic chemical vapor deposition (MOCVD) technology and the effect of different AlGaN buffer layer structures on the properties of Si-based GaN epitaxial materials The prepared GaN materials were characterized by HRXRD, AFM, Raman spectroscopy and optical microscopy. A 3-layer AlGaN buffer layer structure was used to prepare a bright and crack-free GaN epitaxial material with a (002) half-width of 428 arcsec and a surface roughness of 0.194 nm. The results show that the three-layer AlGaN buffer layer structure can effectively reduce the tensile stress and dislocation density of the GaN material, thereby preventing the appearance of surface cracks and improving the crystal quality.