Self-organized morphological and compositional evolution in Al1-xInxN structures on GaN layers

The temperature-dependent microstructural and compositional characteristics of Al_1-xIn_xN structures grown by molecular beam epitaxy (MBE) were investigated to understand the growth behaviors using scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and transmission electron microscopy (TEM) techniques. Self-organized 2D layers and 3D nanostructures were identified in the Al_1-xIn_xN structures grown at 620 °C and 685 °C, while a complete 2D layer formed at 735 °C. As the growth temperature increased from 620 °C to 685 °C, the thickness of the 2D layer increased, while the length of the 3D nanostructures decreased. With increasing temperature, the indium composition in the Al_1-xIn_xN structures decreased from approximately 12 % at 620 °C to 0 % at 735 °C. Compositional fluctuations were observed in the structures grown at 620 °C and 685 °C. Indium-rich clusters resulting from phase separation appeared predominantly in the 3D nanostructures grown at these temperatures. The observed microstructural evolution and compositional fluctuation were interpreted based on growth kinetics. These findings offer valuable insights for optimizing epitaxial growth strategies of ternary compound semiconductors to control morphological features and improve microstructural quality.