Thin films of pentacene were deposited by vacuum sublimation onto amorphous carbon, glass, silicon and mica substrates, then characterized by X-ray and electron diffraction, transmission electron microscopy (TEM) and atomic-force microscopy (AFM). Sub-monolayer films consist of dendritic islands, which change to more compact fractal shapes upon transforming to a multilayer structure (with decrease in surface area) prior to complete coverage of the substrate. Increased crystallite size was obtained by heating the substrate during deposition and by post-deposition annealing. Irradiation with 200-keV electrons was found to destroy the crystallinity of the films after a dose of 0.6∈C/cm 2 (or 2∈C/cm 2 if the specimen is cooled to 90∈K during TEM observation). We argue that, despite this moderate radiation sensitivity, TEM under near-optimal conditions can image monolayers of pentacene with sub-nm resolution.
CITATION STYLE
Qian, H., Malac, M., & Egerton, R. F. (2007). Microscopy of pentacene thin films. Philosophical Magazine, 87(2), 253–266. https://doi.org/10.1080/14786430600953756
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