Regensburg 2010 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 8: Organic Electronics and Photovoltaics I (Joint Session with DS/CPP/O)
HL 8.7: Vortrag
Montag, 22. März 2010, 11:45–12:00, H8
Improving the mobility of the CuPc OFETs by variing the substrate preparation — •Iulia G. Korodi1, Daniel Lehmann1, Michael Hietschold2, and Dietrich R. T. Zahn1 — 1Semiconductor Physics, Chemnitz University of Technology, D-09107 Chemnitz, Germany — 2Solid Surfaces Analysis Group, Chemnitz University of Technology, D-09107 Chemnitz, Germany
Top-contact organic field-effect transistors (OFETs) using Copper Phthalocyanine (CuPc) as active layer were produced under high vacuum conditions (p≤ 5× 10−7 mbar). 20 nm thick organic films were deposited by Organic Molecular Beam Deposition on highly p-doped Si(100) substrates with 100 nm SiO2 as the gate dielectric. Source and drain electrodes of gold were deposited through a shadow mask on top of the organic layer with the substrate cooled by liquid nitrogen.
The performance of the OFETs was tested in vacuum as well as in atmosphere. The highest mobility of CuPc OFETs was found to be µvacuum=(1.5± 0.6) 10−3 cm2/Vs. When the substrate was modified by applying an elevated temperature (130 ∘C) during deposition of the CuPc film the mobility of the OFETs increased by a factor of ≈ 6. The threshold voltage was also improved from a value of VTh=−(15.0± 0.3) V to VTh=−(9.6± 1.4) V for deposition at room and elevated substrate temperatures, respectively. A similar effect on the electrical characteristics was found after modifying the gate dielectric with a self-assembled monolayer of n-octadecyltrichlorosilane. The improved OFET performance with the variation of the substrate conditions will be discussed.
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