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In situ preparation, electrical and surface analytical characterization of pentacene thin film transistors.

Authors
  • Lassnig, R1
  • Striedinger, B2
  • Hollerer, M1
  • Fian, A2
  • Stadlober, B2
  • Winkler, A1
  • 1 Institute of Solid State Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria. , (Austria)
  • 2 Materials Division, Joanneum Research Materials, Franz-Pichler-Straße 30, A-8160 Weiz, Austria. , (Austria)
Type
Published Article
Journal
Journal of Applied Physics
Publisher
AIP Publishing
Publication Date
Sep 21, 2014
Volume
116
Issue
11
Pages
114508–114508
Identifiers
PMID: 25814770
Source
Medline
Language
English
License
Unknown

Abstract

The fabrication of organic thin film transistors with highly reproducible characteristics presents a very challenging task. We have prepared and analyzed model pentacene thin film transistors under ultra-high vacuum conditions, employing surface analytical tools and methods. Intentionally contaminating the gold contacts and SiO2 channel area with carbon through repeated adsorption, dissociation, and desorption of pentacene proved to be very advantageous in the creation of devices with stable and reproducible parameters. We mainly focused on the device properties, such as mobility and threshold voltage, as a function of film morphology and preparation temperature. At 300 K, pentacene displays Stranski-Krastanov growth, whereas at 200 K fine-grained, layer-like film growth takes place, which predominantly influences the threshold voltage. Temperature dependent mobility measurements demonstrate good agreement with the established multiple trapping and release model, which in turn indicates a predominant concentration of shallow traps in the crystal grains and at the oxide-semiconductor interface. Mobility and threshold voltage measurements as a function of coverage reveal that up to four full monolayers contribute to the overall charge transport. A significant influence on the effective mobility also stems from the access resistance at the gold contact-semiconductor interface, which is again strongly influenced by the temperature dependent, characteristic film growth mode.

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