Figure 4

Time-resolved PL results of the graphene/GaN (left) and as-grown GaN (right) at 77 K: Decay curves of FXA center (top), time-resolved PL images (mid) and time evolutional PL spectra (bottom).
The two vertical lines mark the spectral center positions of FXA and DX, respectively. In the images (mid), the emission signal intensity increases as the image color goes from blue, green, to red.