Figure 1: AFM study of the surface integrity of passivated and exposed ultrathin black phosphorus (bP) in ambient conditions.
(a–b) Atomic force microscopy (AFM) scans of a 5-nm-thick bP crystal partly covered with graphene. The images are acquired, respectively, 10 min and 24 h after exposure to ambient conditions. The white dashed lines outline the passivating graphene crystal. (c) AFM scan of a 10-nm-thick bP crystal partly covered with hexagonal BN (hBN) after 5 days in ambient conditions. Scale bar, 4 μm (for all images). (d) Average roughness (Ra) versus time in ambient conditions for the passivated (blue triangles) and exposed (red squares) bP surface of the bP/graphene sample from a,b. The dashed lines are a guide to the eye. (e) Height distribution of the exposed (top) and encapsulated bP surface (bottom) at different times after exposure to ambient conditions for the bP/graphene sample from a,b. (f) Average roughness (Ra) versus time for the passivated (blue triangles) and exposed (red squares) bP surface of the bP/hBN sample from c. The dashed lines are a guide to the eye.
