Field Effect Transistors for Transport

1 FIELD EFFECT TRANSISTORS FOR TRANSPORT PROPERTY STUDIES. 

In a survey of conduction properties it is of interest to divide the conductivity into its two components charge carrier concentration, n or p for electrons and holes, respectively, and the corresponding carrier mobilities in and ip. In this connection field effect transistor (FET) structures are useful. They, however, only cover the low conductivity range, typically 10 S/cm, i.e. essentially undoped material. A central problem in the fabrication are the thin (some ten nanometers) and still homogeneous layers that are needed. The first series of FET experiments addressing the mobility properties of 

FIGURE 20. Mobilities of charge carriers in a spinned P3HT-FET device, in accumulation ( ia) 4 depledon (pd) °4e, during a temperature cycle, RT 130K - 430K RT [98]. 

FET structures including P3 ATs have also been prepared using the Langmuir-Blodgett (LB) technique [100]. Thin films of P3HT mixed with 40 mol % arachidic acid to facilitate LB deposition, exhibit a mobility of 7 x 10 cm /Vs. These LB-structures may be considered as models - on a molecular level and in a highly ordered form - of blend materials to be discussed below. 

FIGURE 21. dc conductivity vs. inverse temperature, in FeCl3 doped EVA/P30T samples 

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Paloheimo, J., Punkka, E., Stubb, H and Kuivalainen, P. "Polymer field-effect transistors for transport property studies.", submitted for publication in Proc. of NATO ASI "Lower Dimensional Systems and Molecular Electronics", Spetses, Greece 12-23 June 1989. Ed. R M Metzger. Plenum Press 1990. 

Organic Field-Effect Transistors for Spin-Polarised Transport... 

This list can be divided into three main classes based mainly on function and redox state. First, applications that utilize the conjugated polymer in its neutral state are often based around their semi-conducting properties, as in electronic devices such as field effect transistors or as the active materials in electroluminescent devices. Secondly, the conducting forms of the polymers can be used for electron transport, electrostatic charge dissipation, and as EMI-shielding mate-... 

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