Asymmetric grain distribution in phthalocyanine thin films

Journal Article · Sun Nov 01 00:00:00 EDT 2009 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PHYSREVB.80.174118· OSTI ID:21294465

Gentry, K Paul; Gredig, Thomas; Schuller, Ivan K ^[1]

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1. Department of Physics and Astronomy, California State University-Long Beach, 1250 Bellflower Boulevard, Long Beach, California 90840 (United States)

Many electronic and optical properties of organic thin films depend on the precise morphology of grains. Iron phthalocyanine thin films are grown on sapphire substrates at different temperatures to study the effect of grain growth kinematics and to experimentally quantify the grain size distribution in organic thin films. The grain size is measured with an atomic force microscope and the data is processed and analyzed with well-known image segmentation algorithms. For relevant statistics, over 3000 grains are evaluated for each sample. The data show pronounced asymmetric grain growth with increasing deposition temperature from almost spherical grains at room temperature to elongated needlelike shapes at 260 deg. C. The average size along the major axis increases from 35 to 200 nm and along the minor axis from 25 to 90 nm. The distribution is almost symmetric at low-deposition temperatures, but becomes lognormal at higher temperatures. Strikingly, the major axis and minor axis of the elliptically shaped grains have different distributions at all temperatures due to the planar asymmetry of the molecule.

• OSTI ID: 21294465
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Vol. 80, Issue 17; Other Information: DOI: 10.1103/PhysRevB.80.174118; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALGORITHMS
ASYMMETRY
ATOMIC FORCE MICROSCOPY
DISTRIBUTION
ELECTRICAL PROPERTIES
GRAIN GROWTH
GRAIN SIZE
IRON
MOLECULAR BEAM EPITAXY
OPTICAL PROPERTIES
ORGANIC SEMICONDUCTORS
PHTHALOCYANINES
ROUGHNESS
SAPPHIRE
SPHERICAL CONFIGURATION
SUBSTRATES
SURFACES
SYMMETRY
TEMPERATURE RANGE 0273-0400 K
THIN FILMS