(a) Schematic diagram of the individualization process: ① initial dispersion: 0.3wt % of of water (50 ml); ② homonization: low power sonication for 10 min at 140 W and ultrasonication for 30 min at 540 W using tip sonicator; ③ individualization: centrifugation for 2.5 h with 150 000 g; ④ finally, individualized solution: the upper 30% of the was carefully decanted. (b) Absorption spectra of individually dispersed SWNTs. The absorption curve over 1000 nm includes the fluorescence peaks of the individualized semiconducting nanotubes.
Schematics of the experimental setup of (a) micronozzle based spin casting and (b) spray method.
FESEM images of the SWNT layer according to the surface functionalization of the substrate: (a) 5000 rpm spin casting without functionalization (50 000×), (b) 5000 rpm spin casting with 10 mM functionalization (50 000×), (c) spray method without functionalization (800×), and (d) spray method with 10 mM functionalization (50 000×).
The adhesion mechanism of (a) the pure SWNT and (b) the surfactant wrapped SWNT on a bare wafer without APTES functionalization.
Comparison of the AFM images of the SWNT layers depending on the concentration of the substrate functionalization (rotation speed: 5000 rpm): (a) 1 mM concentration at center area, (b) 1 mM concentration at edge area, (c) 10 mM concentration at center area, (d) 10 mM concentration, edge area, (e) 100 mM concentration at center area, and (f) 100 mM concentration at edge area.
AFM images of the SWNT layer according to the variations in physical experimental condition for SWNT deposition: (a) 1000 rpm velocity, center area, (b) 1000 rpm velocity, edge area, (c) 3000 rpm velocity, center area, (d) 3000 rpm velocity, edge area, (e) 5000 rpm velocity, center area, (f) 5000 rpm velocity, edge area, (g) spray method, center area, and (h) spray method, edge area.
633 nm Raman spectra analysis around the radial breathing mode for the resultant SWNT monolayer. The upper side is the result on pristine SWNTs on nonfunctionalized substrate and the lower side is the resultant SWNT layer on functionalized substrate.
Comparison of rms roughness according to the various experimental conditions for the SWNT layer.
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