sapphire afm at atomic resolution
Lattice-resolution images of single-crystal a-alumina (sapphire) (0001) surfaces have been obtained using contact-mode AFM under
ambient conditions. It was found that the hexagonal surface lattice has a periodicity of 0.47 ± 0.11 nm, which is identical to that reported
previously when the same surface was imaged in water. Large lattice corrugations (as high as 1 nm) were observed, but were concluded to
be imaging artifacts because of the strong friction which causes additional deflection of the cantilever. The additional deflection of the
cantilever is registered by the detector of the optical beam-deflection AFM resulting in an overestimation of the height at each lattice
point. Abrupt changes were also resolved in the topography including honeycomb patterns and a transition from 2D lattices to 1D
parallel stripes, with scanning direction. These phenomena can be explained by the commensurate sliding between the tip and sapphire
surface due to the strong contact force.