Fig.3 (c) shows the SixOyFz located at the border of bowl-like structures
are much less than that shown in Fig.2 (c), and Fig.3 (b) shows the
top of the ridge-like structures are more peaked than that shown in
Fig.2 (b), these can both in dicate that most of adsorbates are cleared
a way after the post-cleaning process. Meanwhile, thesurface
morphology, including both the bowl-like structures and the
ridge-like structures, remain almost unchanged.