1：Experimental Design and Method Selection:

The study involves the growth of AlGaN quantum dots by molecular beam epitaxy using solid sources for Ga and Al elements and ammonia (NH3) as the nitrogen source. The evolution of the GaN layer morphology was monitored in situ by reflection high energy electron diffraction (RHEED).

2：Sample Selection and Data Sources:

The samples were grown on (0001) sapphire substrates, with an Al0.5Ga0.5N (0001)-oriented layer followed by the fabrication of the GaN QD at a temperature of 800°C.

3：5Ga5N (0001)-oriented layer followed by the fabrication of the GaN QD at a temperature of 800°C. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Molecular beam epitaxy (MBE) in a RIBER 32 reactor, solid sources for aluminium and gallium, and ammonia (NH3) as nitrogen precursor.

4：Experimental Procedures and Operational Workflow:

The growth mechanisms of GaN on Al0.5Ga0.5N were investigated based on the evolution of the GaN layer morphology, monitored in situ by RHEED. The variation of the intensity, which corresponds to the integrated intensity of two different regions of the RHEED diagram, was recorded.

5：5Ga5N were investigated based on the evolution of the GaN layer morphology, monitored in situ by RHEED. The variation of the intensity, which corresponds to the integrated intensity of two different regions of the RHEED diagram, was recorded. Data Analysis Methods:

5. Data Analysis Methods: The photoluminescence (PL) properties of the samples were studied and compared between 12 K and 300 K.