SiN插入层对GaN外延膜应力和光学质量的影响

摘要

High quality GaN epilayers have been grown on 6H-SiC substrate by metal organic chemical vapor deposition (MOCVD) using an in situ porous SiNx interlayer.It was found that the SiNx interlayer played a very important role in strain relief and the enhancement of quality of GaN epilayer.Optical microscope studies revealed that the crack line density was reduced to 0.29 mm-1.Furthermore,the in-plane stress of 1.58 × 10-3 was measured by Raman spectra,representing a significant strain relief.The relaxation was assisted by the reduction of dislocation density.Finally,a linear coefficient characterizing the relationship between the band gap and the biaxial stress of the GaN epilayer was obtained.%研究了MOCVD系统中原位SiN插入层对GaN薄膜应力和光学性质的影响.采用SiN插入层后,GaN薄膜的裂纹数量大大减少,薄膜所承受的张应力得到了一定的释放.同时,GaN薄膜的缺陷密度降低一倍,晶体质量得到了极大的改善.研究表明,位错密度的降低在GaN薄膜中留存较大的残余应力,补偿了降温过程中所引入的张应力.同样,随着SiN插入层的应用,低温PL谱的半峰宽降低,薄膜光学质量提高.最后研究了PL谱发光峰与应力的关系,得到了一个-13.8的线性系数.