1：Experimental Design and Method Selection

InGaN/GaN MQW structures were grown on c-plane sapphire substrate using metal organic chemical vapour deposition (MOCVD) technique by varying the MQW periods.

2：Sample Selection and Data Sources

2-inch c-plane sapphire substrate was used. Trimethylgallium (TMGa), Trimethylindium (TMIn), and ammonia (NH3) were used as precursors.

3：List of Experimental Equipment and Materials

MOCVD (Aixtron200/4RF-S), High resolution X-ray Diffractometer (HRXRD- PANalytical X’Pert Pro MRD), High resolution transmission electron microscopy (HRTEM) (Hitachi, H-9000-NAR, LaB6 filament, 300 kV, point to point resolution: 0.18nm), scanning electron microscopy (SEM, CarlZeiss EVO18), atomic force microscopy (AFM, Park XE-100), Photoluminescence (PL, Spectra Physics), Hall measurement system (ECOPIA, HMS 5000).

4：Experimental Procedures and Operational Workflow

Prior to the growth, the sapphire substrates were thermally cleaned under H2 ambience at 1050oC for 10 min. Subsequently, 25 nm thick GaN nucleation layer (NL) was grown at 520oC with a V/III ratio of 3453. GaN NL was then recrystallized at 1000°C for 1 min. The growth temperature was ramped up to 1010oC and a 2 μm thick n-GaN/GaN was grown. The InGaN/GaN MQW structures were grown at 720oC with V/III ratio 11625 and the GaN barriers at 820oC. Finally, Cp2Mg flow rate for Mg-GaN layer was 300 SCCM grown at 920oC.

5：Data Analysis Methods

The crystalline quality, composition and thickness of the InGaN/GaN MQW structures were determined using HRXRD. The morphology and interfaces were performed using HRTEM. The surface properties and roughness were analyzed by SEM and AFM respectively. PL of the samples were measured at room temperature by 244 nm Ar+ laser. The electrical properties of the samples were measured using hall measurement system.