Thermal stability of Al1−xInxN (0 0 0 1) throughout the compositional range as investigated during in situ thermal annealing in a scanning transmission electron microscope

The thermal stability of Al1-xInxN (0≤x≤1) layers was investigated by scanning transmission electron microscopy (STEM) imaging, electron diffraction, and monochromated valence electron energy loss spectroscopy during in-situ annealing from 750 C to 950 C. The results show two distinct decomposition paths for the Inrichest layers (Al0.28In0.72N and Al0.41In0.59N) that independently lead to transformation of the layers into an In-deficient, nanocrystalline and a porous structure. The In-richest layer (Al0.28In0.72N) decomposes at 750 C, where the decomposition process is initiated by forming In at grain boundaries and is characterized by an activation energy of 0.62 eV. The loss of In from Al0.41In0.59N layer was initiated at 800 C through continuous desorption. No In clusters were observed during this decomposition process, which is characterized by an activation energy of 1.95 eV. Finally, Al-rich Al1-xInxN (x=0.18 and x=0.29) layers were found to resist the thermal annealing, although initial stages of decomposition were observed for the Al0.71In0.29N layer.