【作者】 赵广才；

【导师】 李培咸；

【作者基本信息】 西安电子科技大学 ， 材料物理与化学， 2010， 硕士

【摘要】 本文利用MOCVD设备在几种不同形貌的图形衬底上进行了GaN材料的一系列外延生长实验,结合多种表征手段,研究了温度、压力、流量等生长参数对外延生长GaN材料的结晶质量、表面形貌等的影响,针对关键生长参数进行了优化实验,结合相关理论分析了图形衬底上外延生长的机理。对于不同形貌的图形衬底,利用SEM进行了表面形貌的表征,对外延生长材料的结晶质量采用XRD进行表征分析,结合AFM的结果,分析外延层的表面粗糙度,通过分析外延材料的湿法腐蚀结果比较了图形衬底上不同位置的外延生长材料的缺陷密度。1、对三角形腐蚀坑产生机理、化学腐蚀的时间对外延材料的结晶质量和表面粗糙度产生的影响进行了理论的分析,针对外延片的XRD、SEM、AFM等测试结果优化了腐蚀时间;2、结合AFM结果分析了轰击台阶面的成因,在结晶质量的角度上优化了轰击时间,并结合微台阶理论对斜切结构对外延生长的影响进行了分析,最后优化了外延生长温度这一重要的生长参数;3、采用柱状图形衬底外延生长GaN材料,通过与普通蓝宝石衬底上外延生长的比较,论述了图形衬底上外延生长材料的机理和特点,分析了Ⅴ/Ⅲ与生长速率的关系,依次优化了Ⅴ/Ⅲ、低温缓冲层的生长时间等对材料结晶质量的影响,最后,利用湿法化学腐蚀的方法对比了柱状区域和台面区域处的缺陷分布规律,定性地论述了在柱状图形衬底上外延生长材料的区域分化的特点。更多还原

【Abstract】 Research of high quality GaN epitaxial layer grown on several different kinds of patterned sapphire substrates (PSSs) by MOCVD through a series of growing and testing experiments was developed. The influence of several growth parameters such as temperature、pressure and flux on crystal quality and morphology of epitaxial layer was also researched. Then some key process parameters were optimized and the mechanism of epitaxial growth on PSS was discussed combining with some related theories.For these different kinds of PSSs, SEM was used to characterize the morphology and XRD was used to research the crystal quality ,the surface roughness and the size of dislocation pits were investigated by AFM, also the epitaxial material of different locations of the PSS were compared with the help of chemical etching method.1、Theoretically analysis of the formative mechanism of triangle etching pits and the effect of chemical etching time on the crystal quality and surface roughness of epitaxial layer was processed, meanwhile, the etching time was optimized with the help of XRD、SEM and AFM;2、Formative mechanism of step-surface was analyzed combinee with the results of AFM, etching time was optimized on bese of crystal quality, after explanation of the effect of declining structure on epitaxial layer, growth temperature, the key parameter in epitaxial growth, was optimized;3、Growth mechanism and characteristic of GaN grown on pillar-shape PSS was discussed, the relationship betweenⅤ/Ⅲand growth rate was analyzed, following the optimization ofⅤ/Ⅲ、growth time of LT-uffer layer, regional difference existing in epitaxial layer on piller-shape PSS was qualitative analyzed with the help of chemical etching method.更多还原