Fig. 4

Different defect inspection methods and obtained images of defects. a TEM and HAADF image of SF [43]. bOptical micrograph image after KOH etching [45]. c PL spectrum with and without SF while the inset shows the monochromatic micro-PL mapping at a wavelength of 480 nm. [46]. d A real-color CL SEM image of SF at room temperature [47]. e Raman spectrum of various defects [48]. f Micro-Raman intensity map of the 204 cm⁻¹ peak of a micropipe-related defect [49]