Berlin 2015 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 58: OFETs, OLEDs, and organic optoelectronics
HL 58.9: Talk
Wednesday, March 18, 2015, 18:30–18:45, EW 202
Ultra-high vacuum fabrication and characterization of organic thin film transistors: In-situ electrical and surface sensitive analysis on temperature effects and layer growth — •Roman Lassnig1, Michael Hollerer1, Bernd Striedinger2, Alexander Fian2, Barbara Stadlober2, and Adolf Winkler1 — 1Institute of Solid State Physics, Graz University of Technology, Austria — 2Materials Division, Joanneum Research, Austria
Many of the underlying principles affecting critical organic field effect transistor (OFET) parameters such as performance and lifetime are not fully understood to the present date. We present analysis on the formation, structure and stability of the semiconducting layer in pentacene OFETs, through a unique combination of in-situ layer deposition, real-time electrical and surface analytical characterization, during and subsequent to the deposition process itself. All investigations have been performed under ultra-high vacuum conditions at temperatures ranging from 125 K up to semiconductor desorption. In-situ Auger electron spectroscopy (AES) and thermal desorption spectroscopy (TDS) were performed parallel to the electrical investigations. Ex-situ atomic force microscopy allowed direct connections to be made between growth mode, morphology and charge transport mechanisms. Of special interest was the onset of the OTFT functionality as a function of layer thickness in combination with sample pretreatment. In addition, the evaluation of, coverage and growth temperature dependent, linear and saturation charge carrier mobilities proved to be of great interest in regard to contact resistance assessments.