Charge transport in organic and polymer thin-film transistors: recent issues

Interest in organic and polymer thin film transistors (OTFTs and PTFTs; hereafter both are called PTFTs) has grown rapidly in the last decade. However, the theory of charge transport in PTFTs lags experiments, so it is difficult to provide the required feedback to device designers and technologists. Therefore, the authors present an analysis of charge transport in PTFTs. It is based on extensive published theoretical and experimental material. The discussion includes examples exploring the trend in experimental results. It is noted that because of the similarity in device structures and current-voltage characteristics between PTFTs and inorganic metal-oxide-semiconductor (MOS) field-effect transistors (FETs), the MOS theory and model have been used extensively in analysing the properties of PTFTs. The MOS model has also been significantly modified to obtain agreement with experiments, and these modifications are discussed. However, recent experimental data from state-of-the-art PTFTs reveal that even the adapted MOS model cannot reliably describe the charge transport in PTFTs, because important PTFT properties such as charge injection or charge build-up result in unrealistic values for several physical parameters (e.g. trap concentrations or time constants) in the adapted MOS model. Therefore, the injection-drift limited model (IDLM) is introduced in this work in an attempt to bring the theory of charge transport and the experimental data closer. The IDLM incorporates the important charge transport phenomena in PTFTs injection, drift and charge build-up. The paper concludes with a discussion of unsolved problems in charge transport in PTFTs.

[1]  E. Montroll,et al.  Anomalous transit-time dispersion in amorphous solids , 1975 .

[2]  Thomas N. Jackson,et al.  Modeling of organic thin film transistors of different designs , 2000 .

[3]  J. Rogers,et al.  Flicker noise properties of organic thin-film transistors , 2000 .

[4]  Paul Heremans,et al.  Modeling of transport in polycrystalline organic semiconductor films , 2003 .

[5]  Eric W. Forsythe,et al.  Current–voltage characteristic of organic light emitting diodes , 1998 .

[6]  M. Jamal Deen,et al.  Noise and charge transport in polymer thin film structures , 2003, SPIE International Symposium on Fluctuations and Noise.

[7]  Gilles Horowitz,et al.  The oligothiophene‐based field‐effect transistor: How it works and how to improve it , 1990 .

[8]  A. R. Brown,et al.  Logic Gates Made from Polymer Transistors and Their Use in Ring Oscillators , 1995, Science.

[9]  Yong Qiu,et al.  H2O effect on the stability of organic thin-film field-effect transistors , 2003 .

[10]  S. Holdcroft,et al.  Reversible charge transfer complexes between molecular oxygen and poly(3-alkylthiophene)s† , 1994 .

[11]  F. Hooge.  1/f noise sources , 1994 .

[12]  Fabrication and characterization of field effect transistors using donor and acceptor stacked layers , 1998 .

[13]  M. H. Kazemeini,et al.  Electrical characterization of polymer-based FETs fabricated by spin-coating poly(3-alkylthiophene)s , 2004, IEEE Transactions on Electron Devices.

[14]  Bonwon Koo,et al.  Characteristics of Pentacene Organic Thin Film Transistors with Gate Insulator Processed by Organic Molecules , 2002 .

[15]  P. Blom,et al.  Comparative study of hole transport in poly(p-phenylene vinylene) derivatives , 2000 .

[16]  Robert A. Street,et al.  Pentacene thin film transistors on inorganic dielectrics: Morphology, structural properties, and electronic transport , 2003 .

[17]  P. Blom,et al.  Simultaneous measurement of electron and hole mobilities in polymer light-emitting diodes , 2000 .

[18]  Christos D. Dimitrakopoulos,et al.  Molecular beam deposited thin films of pentacene for organic field effect transistor applications , 1996 .

[19]  A. van der Ziel,et al.  Unified presentation of 1/f noise in electron devices: fundamental 1/f noise sources , 1988, Proc. IEEE.

[20]  Raoul Schroeder,et al.  Improving organic transistor performance with Schottky contacts , 2004 .

[21]  I. Balberg,et al.  Bipolar phototransport in π-conjugated polymer /C60 composites , 2001 .

[22]  Debra J. Mascaro,et al.  Organic thin-film transistors: A review of recent advances , 2001, IBM J. Res. Dev..

[23]  Daniel Gamota,et al.  Printed Organic and Molecular Electronics , 2004 .

[24]  Control of FET Characteristics by Electric Field During Charge Transfer Complex Deposition , 2002 .

[25]  P. Blom,et al.  Dispersive hole transport in poly(p-phenylene vinylene) , 1998 .

[26]  P. Blom,et al.  Local charge carrier mobility in disordered organic field-effect transistors , 2003 .

[27]  Stephen Y. Chou,et al.  Fabrication of 70 nm channel length polymer organic thin-film transistors using nanoimprint lithography , 2002 .

[28]  D. Taylor,et al.  Interface states and depletion-induced threshold voltage instability in organic metal-insulator-semiconductor structures , 2004 .

[29]  W. Fix,et al.  Fast polymer integrated circuits , 2002 .

[30]  J. A. Nichols,et al.  Potential imaging of pentacene organic thin-film transistors , 2003 .

[31]  M. Shur,et al.  1/f noise in pentacene organic thin film transistors , 2000 .

[32]  Robert A. Street,et al.  Morphology and electronic transport of polycrystalline pentacene thin-film transistors , 2003 .

[33]  C. Daniel Frisbie,et al.  Surface potential profiling and contact resistance measurements on operating pentacene thin-film transistors by Kelvin probe force microscopy , 2003 .

[34]  Gilles Horowitz,et al.  An analytical model for organic‐based thin‐film transistors , 1991 .

[35]  N. Karl,et al.  Charge carrier transport in organic semiconductors , 2003 .

[36]  Fabio Biscarini,et al.  Spatially correlated charge transport in organic thin film transistors. , 2004, Physical review letters.

[37]  M. J. Deen,et al.  Low-frequency noise in polymer thin-film transistors , 2004 .

[38]  Gilles Horowitz,et al.  GATE VOLTAGE DEPENDENT MOBILITY OF OLIGOTHIOPHENE FIELD-EFFECT TRANSISTORS , 1999 .

[39]  S. Holdcroft,et al.  Electrical characteristics and photolytic tuning of poly(3-hexylthiophene) thin film metal–insulator–semiconductor field-effect transistors (MISFETs) , 1992 .

[40]  H.C.F. Martens,et al.  Crossover from space-charge-limited to recombination-limited transport in polymer light-emitting diodes , 2001 .

[41]  S. Im,et al.  Hole transport in amorphous-crystalline-mixed and amorphous pentacene thin-film transistors , 2002 .

[42]  M. Yokoyama,et al.  CHARGE INJECTION CONTROLLED ORGANIC TRANSISTOR , 2002, NIP & Digital Fabrication Conference.

[43]  Ognian Marinov,et al.  Variable current transport in polymer thin film transistors , 2004 .

[44]  Torahiko Ando,et al.  Macromolecular electronic device: Field-effect transistor with a polythiophene thin film , 1986 .

[45]  Robert A. Street,et al.  Additive jet printing of polymer thin-film transistors , 2003 .

[46]  P. Blom,et al.  Voltage-modulated millimeter-wave spectroscopy on a polymer diode: mesoscopic charge transport in conjugated polymers. , 2001, Physical review letters.

[47]  S. Holdcroft,et al.  Nature of Impurities in .pi.-Conjugated Polymers Prepared by Ferric Chloride and Their Effect on the Electrical Properties of Metal-Insulator-Semiconductor Structures , 1995 .

[48]  J. C. Scott,et al.  Metal–organic interface and charge injection in organic electronic devices , 2003 .

[49]  Robert A. Street,et al.  Hole transport in polycrystalline pentacene transistors , 2002 .

[50]  T. Kurokawa,et al.  Electrical properties of polyacetylene/polysiloxane interface , 1983 .

[51]  Richard H. Friend,et al.  Close look at charge carrier injection in polymer field-effect transistors , 2003 .

[52]  Dago M. de Leeuw,et al.  Field-effect transistors made from solution-processed organic semiconductors , 1997 .

[53]  Jin Jang,et al.  Organic Thin-Film Transistors Fabricated on Plastic Substrates with a Polymeric Gate Dielectrics , 2003 .

[54]  Sampath Purushothaman,et al.  High-performance bottom electrode organic thin-film transistors , 2001 .

[55]  M. J. Deen,et al.  Low-frequency noise in polymer transistors , 2001 .

[56]  J. A. Misewich,et al.  A field effect transistor based on the Mott transition in a molecular layer , 1996 .

[57]  Raoul Schroeder,et al.  A study of the threshold voltage in pentacene organic field-effect transistors , 2003 .

[58]  S. Scheinert,et al.  Analyzes of field effect devices based on poly(3-octylthiophene) , 2003 .

[59]  Zhenan Bao,et al.  Organic field‐effect transistors with high mobility based on copper phthalocyanine , 1996 .

[60]  Luisa Torsi,et al.  Organic field-effect bipolar transistors , 1996 .

[61]  George G. Malliaras,et al.  Temperature- and field-dependent electron and hole mobilities in polymer light-emitting diodes , 1999 .

[62]  P. Blom,et al.  Electric-field and temperature dependence of the hole mobility in poly(p-phenylene vinylene) , 1997 .

[63]  M. Deen.  Organic Semiconductor Devices , 1999 .

[64]  Thomas N. Jackson,et al.  Pentacene-based organic thin-film transistors , 1997 .

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

[66]  L.K.J. Vandamme,et al.  1/f noise in pentacene and poly-thienylene vinylene thin film transistors , 2002 .

[67]  Robert A. Street,et al.  Contact effects in polymer transistors , 2002 .

[68]  Norbert Koch,et al.  Conjugated organic molecules on metal versus polymer electrodes: Demonstration of a key energy level alignment mechanism , 2003 .

[69]  V. M. Pudalov,et al.  Single-crystal organic field effect transistors with the hole mobility ∼8 cm2/V s , 2003 .

[70]  Robert A. Street,et al.  Polymer thin-film transistors with chemically modified dielectric interfaces , 2002 .

[71]  Walter Riess,et al.  Transient and steady-state behavior of space charges in multilayer organic light-emitting diodes , 2001 .

[72]  Henrique L. Gomes,et al.  Bias-induced threshold voltages shifts in thin-film organic transistors , 2004 .

[73]  R. Singh,et al.  Prospects of manufacturing organic semiconductor-based integrated circuits , 2001 .

[74]  Henrique L. Gomes,et al.  Effect of oxygen on the electrical characteristics of field effect transistors formed from electrochemically deposited films of poly(3-methylthiophene) , 1991 .