Critical Evaluation of Organic Thin-Film Transistor Models

The thin-film transistor (TFT) is a popular tool for determining the charge-carrier mobility in semiconductors, as the mobility (and other transistor parameters, such as the contact resistances) can be conveniently extracted from its measured current-voltage characteristics. However, the accuracy of the extracted parameters is quite limited, because their values depend on the extraction technique and on the validity of the underlying transistor model. We propose here a new approach for validating to what extent a chosen transistor model is able to predict correctly the transistor operation. In the two-step fitting approach we have developed, we analyze the measured current-voltage characteristics of a series of TFTs with different channel lengths. In the first step, the transistor parameters are extracted from each individual transistor by fitting the output and transfer characteristics to the transistor model. In the second step, we check whether the channel-length dependence of the extracted parameters is consistent with the underlying model. We present results obtained from organic TFTs fabricated in two different laboratories using two different device architectures, three different organic semiconductors and five different materials combinations for the source and drain contacts. For each set of TFTs, our approach reveals that the state-of-the-art transistor models fail to reproduce correctly the channel-length-dependence of the transistor parameters. Our approach suggests that conventional transistor models require improvements in terms of the charge-carrier-density dependence of the mobility and/or in terms of the consideration of uncompensated charges in the carrier-accumulation channel.

[1]  M. Vissenberg,et al.  Theory of the field-effect mobility in amorphous organic transistors , 1998, cond-mat/9802133.

[2]  W. Shockley,et al.  A Unipolar "Field-Effect" Transistor , 1952, Proceedings of the IRE.

[3]  H. Yamada,et al.  Extraction of contact resistance and channel parameters from the electrical characteristics of a single bottom-gate/top-contact organic transistor , 2016 .

[4]  Joachim N. Burghartz,et al.  Small contact resistance and high-frequency operation of flexible low-voltage inverted coplanar organic transistors , 2019, Nature Communications.

[5]  D. Marquardt An Algorithm for Least-Squares Estimation of Nonlinear Parameters , 1963 .

[6]  P. Heremans,et al.  Analytic model of hopping mobility at large charge carrier concentrations in disordered organic semiconductors: Polarons versus bare charge carriers , 2007 .

[7]  J. Carrabina,et al.  Uniform, high performance, solution processed organic thin-film transistors integrated in 1 MHz frequency ring oscillators , 2018 .

[8]  Takao Someya,et al.  Contact resistance and megahertz operation of aggressively scaled organic transistors. , 2012, Small.

[9]  Takao Someya,et al.  Dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (DNTT) thin-film transistors with improved performance and stability , 2011 .

[10]  Jihoon Kang,et al.  Tuning of Ag work functions by self-assembled monolayers of aromatic thiols for an efficient hole injection for solution processed triisopropylsilylethynyl pentacene organic thin film transistors , 2008 .

[11]  Henning Sirringhaus,et al.  Simultaneous extraction of charge density dependent mobility and variable contact resistance from thin film transistors , 2014, 1402.5241.

[12]  Gerold W. Neudeck,et al.  An experimental study of the source/drain parasitic resistance effects in amorphous silicon thin film transistors , 1992 .

[13]  Transition-Voltage Method for Estimating Contact Resistance in Organic Thin-Film Transistors , 2010, IEEE Electron Device Letters.

[14]  L. Colalongo,et al.  Single-transistor method for the extraction of the contact and channel resistances in organic field-effect transistors , 2014 .

[15]  Jonathon Howard,et al.  Drawing an elephant with four complex parameters , 2010 .

[16]  Marco Sampietro,et al.  Modeling of organic thin film transistors: Effect of contact resistances , 2007 .

[17]  H. Klauk,et al.  Detailed analysis and contact properties of low-voltage organic thin-film transistors based on dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (DNTT) and its didecyl and diphenyl derivatives , 2016 .

[18]  U. Zschieschang,et al.  Organic Thin-Film Transistors: Part II—Parameter Extraction , 2009, IEEE Transactions on Electron Devices.

[19]  Joachim N. Burghartz,et al.  Contact properties of high-mobility, air-stable, low-voltage organic n-channel thin-film transistors based on a naphthalene tetracarboxylic diimide , 2013 .

[20]  Gilles Horowitz,et al.  Temperature and gate voltage dependence of hole mobility in polycrystalline oligothiophene thin film transistors , 2000 .

[21]  U. Zschieschang,et al.  Organic Thin-Film Transistors: Part I—Compact DC Modeling , 2009, IEEE Transactions on Electron Devices.

[22]  Jan Genoe,et al.  On the Extraction of Charge Carrier Mobility in High‐Mobility Organic Transistors , 2016, Advanced materials.

[23]  P. Lugli,et al.  Modeling of Short-Channel Effects in Organic Thin-Film Transistors , 2008, IEEE Transactions on Electron Devices.

[24]  Jun Li,et al.  Electric-field enhanced thermionic emission model for carrier injection mechanism of organic field-effect transistors: understanding of contact resistance , 2017 .

[25]  R. B. Hall The Poole-Frenkel effect , 1971 .

[26]  Jerzy Kanicki,et al.  Performance of thin hydrogenated amorphous silicon thin‐film transistors , 1991 .

[27]  John E. Anthony,et al.  Contact-induced crystallinity for high-performance soluble acene-based transistors and circuits. , 2008, Nature materials.

[28]  Mario Caironi,et al.  Charge Injection in Solution‐Processed Organic Field‐Effect Transistors: Physics, Models and Characterization Methods , 2012, Advanced materials.

[29]  B. Stadlober,et al.  Embedded Dipole Self‐Assembled Monolayers for Contact Resistance Tuning in p‐Type and n‐Type Organic Thin Film Transistors and Flexible Electronic Circuits , 2018, Advanced Functional Materials.

[30]  H. Klauk,et al.  Nonlinear Contact Effects in Staggered Thin-Film Transistors , 2017 .

[31]  Toshihiro Okamoto,et al.  Wafer-scale, layer-controlled organic single crystals for high-speed circuit operation , 2018, Science Advances.

[32]  Yang Han,et al.  Recent Progress in High‐Mobility Organic Transistors: A Reality Check , 2018, Advanced materials.

[33]  P. Blom,et al.  Unified description of charge-carrier mobilities in disordered semiconducting polymers. , 2005, Physical review letters.

[34]  Thomas N Jackson,et al.  Mobility overestimation due to gated contacts in organic field-effect transistors , 2016, Nature Communications.

[35]  Tse Nga Ng,et al.  Current Status and Opportunities of Organic Thin-Film Transistor Technologies , 2017, IEEE Transactions on Electron Devices.