Figure 2

Scanning probe microscopy images of (a) NaF (0 nm)/CZTSSe (b) NaF (15 nm)/CZTSSe (c) NaF (30 nm)/CZTSSe thin-films deposited by sputtering method. The NaF/CZTSSe thin-film surface shows the higher grain size.
Scanning probe microscopy images of (a) NaF (0 nm)/CZTSSe (b) NaF (15 nm)/CZTSSe (c) NaF (30 nm)/CZTSSe thin-films deposited by sputtering method. The NaF/CZTSSe thin-film surface shows the higher grain size.