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Morphology of α-hexathienyl thin-film-transistor films

Published online by Cambridge University Press:  03 March 2011

A.J. Lovinger
Affiliation:
AT&T Bell Laboratories, Murray Hill, New Jersey 07974
D.D. Davis
Affiliation:
AT&T Bell Laboratories, Murray Hill, New Jersey 07974
R. Ruel
Affiliation:
AT&T Bell Laboratories, Murray Hill, New Jersey 07974
L. Torsi
Affiliation:
AT&T Bell Laboratories, Murray Hill, New Jersey 07974
A. Dodabalapur
Affiliation:
AT&T Bell Laboratories, Murray Hill, New Jersey 07974
H.E. Katz
Affiliation:
AT&T Bell Laboratories, Murray Hill, New Jersey 07974
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Abstract

We have studied the morphology of thin films of α-hexathienyl (α-6T), a hexamer of thiophene that is a very promising material for thin-film-transistor applications. Using electron- and atomic-force microscopies, we found that on both rigid (Si/SiO2 and glass) and flexible (polyimide) substrates, evaporated films show an apparently random, polycrystalline morphology. The crystals are lamellar, ca. 100-200 nm in lateral dimensions and 15-30 nm in thickness, and exhibit irregular boundaries. Nevertheless, electron-diffraction evidence from such films indicates that the constituent molecules are deposited preferentially end-on and assume a normal or nearly normal orientation with respect to their substrates. Rapid high-temperature annealing causes growth of much larger (μm-sized) crystalline grains and a partial transformation to a high-temperature polymorph; however, this process leads to formation of gaps in the film, which may cause deterioration of electronic performance.

Type
Articles
Copyright
Copyright © Materials Research Society 1995

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References

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