AFM Metrology for Patterned Al Film and Molecular Steps of Rubrene Crystal
Rubrene Crystal
We scan many different localities on rubrene surface, and found that the crystal is very smooth and characterized by regular steps
separated by different spacings (0.1 -1 μm). Figure 7 (A), (C), and (E) are topography images; the right columns (B), (D), (F) are
corresponding phase images. Figure 7(A) and 7(C) were collected in different areas, showing variable spacings. Figure 7E is a 1 ×
1 μm scan for quantitative analysis. We found the step height is typically around 1.3 nm. Examples of results are shown in Figure 8B,
where the two steps would combine to 2.609 nm.
Figure 6: Grain Analysis for the Al film indicated in Figure 1A: (A, B) 600 × 600 nm topography and phase image; (C, D) corresponding
grain analysis. The mode of the Max_Height distribution is ~7 nm, and the radius distribution mode is ~ 8.5 nm.
Figure 7: Rubrene Crystal Surface. The left column (A), (C), and (E) are topography images; the right column (B), (D), (F) are corresponding phase images.
(A) and (C) was collected in different areas, showing variable spacings.
Figure 8: (A) A 3-D view of the same structure as Figure 7E. (B) Z-height analysis for the steps. The pair 1 shows a step of 1.293 nm height, and the pair 2
shows a step of 1.316 nm height. The step height is typically ~1.3 nm. The scan lines show super-low noise performance of the system, compared to the
1.13 A height.
Conclusion
This measurement has shown example results of topography and phase images for the patterned Al Josephson junctions and grain
analysis. Al film that does not have top layer deposits is typically ~25 nm thick. The top layer of Al wire is ~25 nm higher than the bottom
layer. The linewidth varies from 100 to 140 nm. Grain analysis for a phase image of Al grain structures shows an average radius
of 10 nm and average Max_height of 7.29 nm. The surface of rubrene crystal was found very smooth and one step was typically 1.3
nm high.
Pacific Nanotechnology’s Nano-R2™ AFM is shown fully capable for analysis and study of Josephson junctions, grain structure of Al film,
and atomic steps of rubrene crystal. The scan lines indicated by the black arrow in Figure 8B, compared with the 1.13 A height, have
demonstrated the super-low noise performance of the system.
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