Fig. 2(a): the SEM-CL image of the cross-section FIB specimen. Fig. 2(c): Data set of the the mean CL spectrum extracted from CL-Data-withoutfeature.bin in .csv format

Fig. 3(a): data set of the mean spectrum taken near the SiC/GaN interface of the cross-section FIB specimen extracted from CL-Data-withoutfeature.bin in .csv format Fig. 3(b): data set of the mean spectrum taken just below the InxGa1-xN MQW of the cross-section FIB specimen extracted from CL-Data-withoutfeature.bin in .csv format Fig. 3(c): data set of the mean spectrum taken at the InxGa1-xN MQW layer of the cross-section FIB specimen extracted from CL-Data-withoutfeature.bin in .csv format

Fig. 4(a): data set of the Gaussian fitted peak emission energy map for GaN NBE at around 3.27 eV of the cross-section FIB specimen, extracted from CL-Data-withoutfeature.bin in .csv format Fig. 4(b): data set of the Gaussian fitted peak emission energy map for QW emissions at around 2.71 eV of the cross-section FIB specimen, extracted from CL-Data-withoutfeature.bin in .csv format Fig. 4(c): data set of the spectrum of a selected location where the Gaussian fit does not accurately depict the behaviour of the MQW, extracted from CL-Data-withoutfeature.bin in .csv format

Fig. 5(a): the HAADF STEM image of the cross-section FIB specimen including a protruding MQW structure, named feature A. Fig. 5(insert): the panchromatic CL image of the cross-section FIB specimen corresponding to Fig. 5(a),extracted from CL-Data-with feature.bin Fig. 5(b): data set of the spectrum of feature A, extracted from CL-Data-with feature.bin in .csv format Fig. 5(c): data set of the spectrum of the flat MQW area in Fig. 5(a), extracted from CL-Data-with feature.bin in .csv format

Fig. 6(1): the diffraction patterns taken from GaN film Fig. 6(2): the diffraction patterns taken from feature A Fig. 6(3): the diffraction patterns taken from SFs below feature A Fig. 6(4): the diffraction patterns taken from the boundary of feature A

Fig. 7(a): the HAADF STEM image of feature A

Fig. 8: Dataset of the EDS map of Indium taken at feature A in .ser format. The raw data can be opened with the open source software ImageJ and other electron microscopy software packages.

CL-Data-with feature.bin: Raw data of the CL hyperspectral image in binary format. The data can be opened with the open source LumiSpy Python library

CL-Data-withoutfeature.bin: Raw data of the CL hyperspectral image in binary format. The data can be opened with the open source LumiSpy Python library