The in-situ optical images were recorded using a custom-made optical microscope fitted with a Mitutoyo 10X long-distance objective. The ex-situ optical images were recorded using a standard Olympus optical microscope under ambient conditions. PL and Raman spectra were recorded using a WITec alpha300 R confocal Raman spectrometer under the 1 mW excitation power of a 532 nm laser.