Continuous tuning of the threshold voltage of organic thin-film transistors by a chemically reactive interfacial layer

• Published in: Applied physics. A, Materials science & processing Materials science & processing, 2009-04, Vol.95 (1), p.43-48
• Main Authors: Etschmaier, Harald, Pacher, Peter, Lex, Alexandra, Trimmel, Gregor, Slugovc, Christian, Zojer, Egbert
• Format: Article
• Language: English
• Subjects: Ammonia; Applied physics; Assembly; Carrier mobility; Characterization and Evaluation of Materials; Charge density; Circuit design; Condensed Matter Physics; Current carriers; Devices; Integrated circuits; Machines; Manufacturing; Materials science; Nanotechnology; Optical and Electronic Materials; Oxides; Physics; Processes; Semiconductor devices; Siloxanes; Surfaces and Interfaces; Thin film transistors; Thin Films; Threshold voltage; Transistors; Tuning
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-008-4995-z

For the design and manufacture of complex integrated circuits, control over the threshold voltage of the transistors is essential. In the present contribution, we present a non-invasive method to tune the threshold voltage of organic thin-film transistors after device assembly over a wide range without any significant degradation of the device characteristics. This is realized by incorporating a thin, chemically reactive siloxane layer bonded to the gate oxide. This results in threshold voltages of around 70 V in the as-prepared devices. By exposing a transistor modified in this way to ammonia at different concentrations, the threshold voltage can be tuned in steps of only a few volts. This treatment affects only the charge density at the semiconductor–dielectric interface, leaving the overall shape of the transistor characteristics and the charge-carrier mobility largely unaltered.