中文摘要：

采用有机金属化学气相沉积（MOCVD）在r面蓝宝石衬底上生长a-AlGaN外延膜,研究了AlN插入层对a-AlGaN外延膜的应力和光学性质的影响。根据高分辨X射线衍射（HRXRD）技术和扫描电子显微镜（SEM）我们可以得到,AlN插入层有效地提高了a-AlGaN外延膜的晶体质量并减小了外延膜材料结构的各向异性。由拉曼光谱得到AlN插入层的引入减小了a-AlGaN外延膜的面内压应力,其原因是AlN插入层可以当作衬底有效的调制与减小a-AlGaN外延膜与r面蓝宝石衬底的晶格失配,从而使a-AlGaN的面内应力得到适当释放。对室温下的光致发光进行测量得到AlN插入层的使用使近带边发射峰（NBE）发生了红移,这可能是由于残余应力的减小引起。

英文摘要：

The effect of AlN interlayer on strain states and its effect on optical properties of a-AlGaN epilayers grown by using metal organic chemical vapor deposition（MOCVD） method are investigated.The strain is characterized by the frequency shift based on Raman spectroscopy measurement.The results show that residual strain in a-AlGaN grown on the AlN interlayer is relaxed due to AlN interlayer act as a stable and compliant substrate induced weakening of mechanical strength.Accordingly,the near band edge emission（NBE） peak shows red shift in room temperature photoluminescence measurement.In addition,the introduction of AlN interlayer lead to the red shift of NBE photo-luminescence peaks,which can be contribute to the strain determined by Raman spectra.