Berlin 2008 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 4: Organic Thin Films
DS 4.5: Vortrag
Montag, 25. Februar 2008, 17:15–17:30, H 2013
Organic field effect transistors based on n-conducting PTCDI derivatives — •Daniel Lehmann and Dietrich R.T. Zahn — Chemnitz University of Technology, Semiconductor Physics, D-09107 Chemnitz, Germany
Perylenetetracarboxylic diimide (PTCDI) is a π-conjugated planar perylene derivative. Being used as a red dye pigment in industry, PTCDI is highly available, and due to its n-conducting properties it is a subject of interest as an organic semiconductor for organic field effect transistors (OFETs). We present a comparative study on the electrical properties of top contact OFETs based on different PTCDI derivatives: DiMethyl-PTCDI, DiPhenyl-PTCDI, DiMethoxyethyl-PTCDI, as well as Di3Pentyl-PTCDI. The gate oxide for the devices is a 100 nm thick layer of SiO2 on a highly doped Si(100) substrate. The thickness of the organic layer is in all cases 20 nm. The top contacts were made by depositing gold through a shadow mask. Channel length and width are L=17…186 µm and W=3 mm, respectively. While the initial electron mobility measured in situ is between 10−4 cm2/Vs and 10−8 cm2/Vs depending on the molecule, an annealing of the sample at about 100∘C leads to an increase in mobility typically up to one order of magnitude. This mobility is stable and not influenceable by further bias stress. Furthermore, we report on the influence of air exposure, which leads to a breakdown of the mobility by several orders of magnitude.