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Nano FET | Organic TFT

Organic Thin-Film Transistors

The general contention that organic thin-film transistors (OTFTs) represent a potential Low-cost alternative to their silicon counterpart for large area and flexible electronics has propelled intense research activities in recent years.

.Fig.1 Organic Thin-film Transistors on plastic substrate *source: Phillps, Poly IC

-DC characteristics of OTFTs-

Current – Voltage measurements are a convenient method for DC-characterizing OTFTs. (Fig.2)When evaluating the electrical characteristics of OTFTs, the parameters most often calculated and reported are the field-effect mobility, on/off current ratio, subthreshold slope and Threshold voltage. These parameters ate extracted from the output characteristics (Id-Vd) and transfer characteristics (Id-Vg). (Fig.3)

Fig.2 Cross section view of OTFT and schematic of DC measurements/Conventional material for OTFTs

-AC characteristics of OTFTs-

A lot work in literature has been reported on the characterization and modeling of the DC-characteristic of OTFTs but only limited work has been reported on the AC-characteristics. In the design of analog circuits these AC-characteristic play a very important role. To enable the further development of organic circuits the characterization and modeling of these dynamic properties will be essential.Capacitance-Voltage and Capacitance-Frequency measurement provide important information on the nature of the dielectric/semiconductor interface and dynamic behavior of OTFTs. HMED has to extract the division of the gate capacitance in a gate-source and a gate-drain part of OTFTs for the AC-modeling and limitation of contact region and overlap capacitance has been studied using MIS (Metal-Insulator-Semiconductor) structure .Furthermore, trap state in bulk and interface (trap and release) and fixed charge of different dielectric are suggested.

Fig.4 Cgs, Cgd characteristics of OTFTs