[paper] Compact Modeling of Organic TFT

Jakob Pruefer, Jakob Leise, Ghader Darbandy, Aristeidis Nikolaou, Hagen Klauk, James W. Borchert, Benjamín Iñíguez, Fellow, IEEE, Thomas Gneiting, Member, IEEE

and Alexander Kloes, Senior Member, IEEE

Compact Modeling of Short-Channel Effects in Staggered Organic Thin-Film Transistors

IEEE Transactions on Electron Devices, vol. 67, no. 11, pp. 5082-5090, Nov. 2020

DOI: 10.1109/TED.2020.3021368.

Abstract:This article introduces analytical compact models of short-channel effects in staggered organic thinfilm transistors (TFTs). The effects of subthreshold-swing degradation, threshold-voltage roll-off, and drain-induced barrier lowering (DIBL) on the static current–voltage characteristics of staggered TFTs are extracted from an analytical potential solution of the 2-D problem of the staggered geometry. This solution is derived by using the Schwarz–Christoffel transformation that leads to a complex mapping function linking the staggered geometry to an equivalent in another coordinate system for which an analytical potential solution exists. The commercial TCAD is used to verify the compact models. Finally, the closed-form and physics-based equations are incorporated into an existing compact current model and verified by measurements on staggered organic TFTs with channel lengths as small as 0.4 µm fabricated on flexible plastic substrates by stencil lithography.

Fig:(a) Schematic cross section and (b) simplified geometry 

of the staggered organic TFTs for the TCAD simulations.

Acknowledgement: This work was supported in part by the German Federal Ministry of Education and Research under Grant 13FH015IX6 Strukturnahe Modellierung organischer flexibler KurzkanalTFTs (Structure-Oriented Modeling of Organic FLEXible short-channel TFTs) (SOMOFLEX), in part by the EU H2020 Marie Sklodowska-Curie actions (MSCA) Research and Innovation Staff Exchange (RISE) Project Design Oriented ModellINg for flexible electrOnics (DOMINO) under Grant 645760, and in part by the German Research Foundation (DFG) under Grant KL 1042/9-2 (SPP FFlexCom). 

[paper] oTFT Charge-Based Variability Model

Aristeidis Nikolaou, Ghader Darbandy, Jakob Leise, Jakob Pruefer, James W. Borchert, Michael Geiger, Hagen Klauk, Benjamin Iñiguez, Fellow, IEEE,

and Alexander Kloes, Senior Member, IEEE

Charge-Based Model for the Drain-Current Variability in Organic Thin-Film Transistors 

Due to Carrier-Number and CorrelatedMobility Fluctuation

in IEEE TED (early access), DOI: 10.1109/TED.2020.3018694.

Abstract: In this study, a consistent analytical chargebased model for the bias-dependent variability of the drain current of organic thin-film transistors is presented. The proposed model combines both charge-carrier-numberfluctuation effects and correlated-mobility-fluctuation effects to predict the drain-current variation and is verified using experimental data acquired from a statistical population of organic transistors with various channel dimensions, fabricated on flexible polymeric substrates in the coplanar or the staggered device architecture.

Fig: a) Cross section of the organic TFTs fabricated in the inverted coplanar (bottom-gate, bottom-contact) architecture. b) Transistor channel divided into a noisy element between positions x and x + δx and two noiseless transistors of channel lengths x and L − x, respectively. c) Small-signal representation.

Acknowledgment: This work was supported in part by the German Federal Ministry of Education and Research “SOMOFLEX” under Grant 13FH015IX6 and in part by the German Research Foundation (DFG) under Grant KL 1042/9-2 (SPP FFlexCom). The authors would like to thank AdMOS GmbH for support.