高Al组分AlGaN材料优化生长与组分研究

Optimized growth and composition investigation of AlGaN materials with high Al composition

研究了金属有机化合物化学气相沉积(MOCVD)系统外延高Al组分较厚AlGaN薄膜材料的生长技术。实验发现,AlGaN/GaN结构中的AlGaN材料的相分离现象可能是由于过低的生长V/III以及材料所受的张应力状态所致,而V/III过高时则会出现Al源的并入效率饱和。采用AlN过渡层技术,外延生长了表面无裂纹的45%Al组分较厚(100～200nm)AlGaN薄膜材料。所得材料的Al组分与气相Al组分相同,(0002)面X射线衍射(XRD)双晶摇摆曲线半高宽(FWHM)为376arcsec,并发现AlN过渡层的质量影响着其上AlGaN材料的Al组分与晶体质量。实验观察到AlGaN材料的表面形貌随着样品中Al组分的增加从微坑主导模式逐步转变为微裂主导模式,采用AlN过渡层可延缓这一转变。

The growth technology of AlGaN film with high Al composition and large thickness is investi- gate＆ The phase separation of AlGaN in AlGaN/GaN structure may be due to the too low growth of V/ III and the tensile stress. Meanwhile, with ultra-high V/III, the Al incorporation rate can be saturated. By adopting AlN interlayer,no-crack and thick AIGaN materials with 45% Al composition are grown. The Al composition of this sample is the same as that in gas phase and the width of half height of the rocking curve of （0002） plane is 376＂. It is found that Al composition and crystal quality of the AlGaN film are influenced by the quality of AlN interlayer. It is also seen that as the Al composition increases,the morphology of AlGaN materials changes from micropit mode to microcrack mode, which can be retarded by the AlN interlayer.