1：Experimental Design and Method Selection:

A selective area growth technique was employed to make the periodic arrangement of n-GaN nanowires and GaInN/GaN MQSs. A very low V/III ratio of 20 and a relatively high growth temperature of 1130 °C were used in continuous-flow mode MOVPE for the growth of n-GaN nanowires. After the n-GaN growth, the substrate temperature was lowered to 740 °C, and an undoped AlGaN (10 nm) undershell and the five-period of GaInN (3 nm) / GaN (6 nm) MQS were grown.

2：Sample Selection and Data Sources:

A 30 nm-thick SiO2 mask was deposited by sputtering technique on a n-GaN template/sapphire substrate. The diameter the openings of the SiO2 mask and their pitch are 250 nm and 1,000 nm, respectively.

3：List of Experimental Equipment and Materials:

Scanning electron microscopic equipment (SU70, Hitachi Co., Japan) for CL measurement system.

4：Experimental Procedures and Operational Workflow:

The optical properties of as-grown the GaInN/GaN MQS samples were characterized by CL measurement system attached in a scanning electron microscopic equipment. The probe current was set to 35 μA with an accelerating voltage of 7 kV. The three positions along the height of the MQS grown on the m-plane were measured for the samples with and without the undoped AlGaN underlying shell underneath the MQS.

5：Data Analysis Methods:

The CL peak wavelengths and intensities were analyzed to evaluate the optical properties and the effect of the AlGaN underlying shell.