【摘要】 为了降低MOCVD外延硅基GaN膜层中的应力、减少硅基厚GaN层的微裂;在高温GaN层中插入低温A lN。低温A lN插入层可平衡HT-GaN生长和降温过程引起的张应力,降低厚膜外延层的微裂,已研制出厚度超过1.8微米无微裂GaN外延层。本文重点研究了低温A lN生长温度对HT-GaN材料的影响,给出了较佳的LT-A lN生长温度。采用扫描电子显微镜(SEM),原子力显微镜(AFM)和高分辨率双晶X射线衍射(DCXRD),对样品进行了测试分析。试验和测试结果表明低温A lN的生长温度至关重要,生长温度过低影响GaN晶体质量,甚至不能形成晶体;生长温度过高同样会影响GaN结晶质量,同时降低插入层的应力平衡作用;实验结果表明最佳的LT-A lN插入层的生长温度为680℃左右。更多还原

【Abstract】 The low-temperature-deposited(LT) AlN layer was inserted into high-temperature-deposited(HT) GaN layer in order to reduce stress and cracks of GaN film grown on Si(111) by MOCVD.Low-temperature AlN interlayer can balance HT-GaN layer tensile stress which is aroused during the course of deposition and temperature-falling,and reduce cracks of thick film.The crack-free GaN film with thickness over 1.8μm is grown triumphantly.The influence of low-temperature AlN interlayer deposited temperature on GaN film was studied emphatically in the paper,and the optimum deposited temperature of LT-AlN is given.The microstructures of samples were studied by scanning electron microscopy(SEM),atomic force microscopy(AFM) and high-resolution double crystal X-ray diffraction(DCXRD).The result shown that LT-AlN deposited temperature is very important.The crystal quality of GaN film is inferior even crystal can not be formed if the temperature is too lower.The crystal quality of GaN film is inferior too,and the stress balance influence of LT-AlN is reduced if the temperature is higher.We can conclude that the optimum deposited temperature of LT-AlN is about 680℃.更多还原