High K Capacitors and OFET Gate Dielectrics from Self‐Assembled BaTiO3 and (Ba,Sr)TiO3 Nanocrystals in the Superparaelectric Limit

Nanodielectrics is an emerging field with applications in capacitors, gate dielectrics, energy storage, alternatives to Li-ion batteries, and frequency modulation in communications devices. Self-assembly of high k dielectric nanoparticles is a highly attractive means to produce nanostructured films with improved performance—namely dielectric tunability, low leakage, and low loss—as a function of size, composition, and structure. One of the major challenges is conversion of the nanoparticle building block into a reliable thin film device at conditions consistent with integrated device manufacturing or plastic electronics. Here, the development of BaTi0 3 and (Ba,Sr)Ti0 3 superparaelectric uniform nanocrystal (8-12 nm) films prepared at room temperature by evaporative driven assembly with no annealing step is reported. Thin film inorganic and polymer composite capacitors show dielectric constants in the tunable range of 10-30, dependent on composition, and are confirmed to be superparaelectric. Organic thin film transistor (TFT) devices on flexible substrates demonstrate the readiness of nanoparticle-assembled films as gate dielectrics in device fabrication.

[1]  K. Rabe,et al.  Ferroelectricity at the Nanoscale: Local Polarization in Oxide Thin Films and Heterostructures , 2004, Science.

[2]  O. Auciello,et al.  Ferroelectricity in Ultrathin Perovskite Films , 2004, Science.

[3]  K. Younsi,et al.  The future of nanodielectrics in the electrical power industry , 2004, IEEE Transactions on Dielectrics and Electrical Insulation.

[4]  N. Nuraje,et al.  Open-Bench Method for the Preparation of BaTiO3, SrTiO3, and BaxSr1-xTiO3 Nanocrystals at 80 °C , 2007 .

[5]  Hongkun Park,et al.  Synthesis of single-crystalline perovskite nanorods composed of barium titanate and strontium titanate. , 2002, Journal of the American Chemical Society.

[6]  J. Scott,et al.  Applications of Modern Ferroelectrics , 2007, Science.

[7]  C. Green,et al.  Nanodielectrics - How Much Do We Really Understand? [Feature Article] , 2008, IEEE Electrical Insulation Magazine.

[8]  V. Bulović,et al.  Engineering density of semiconductor-dielectric interface states to modulate threshold voltage in OFETs , 2006, IEEE Transactions on Electron Devices.

[9]  R. Newnham,et al.  Intrinsic Size Effects in a Barium Titanate Glass-Ceramic , 2005 .

[10]  Sampath Purushothaman,et al.  Low-Voltage, High-Mobility Pentacene Transistors with Solution-Processed High Dielectric Constant Insulators , 1999 .

[11]  Susan Trolier-McKinstry,et al.  The Properties of Ferroelectric Films at Small Dimensions , 2000 .

[12]  W. Krautschneider,et al.  Spin-cast composite gate insulation for low driving voltages and memory effect in organic field-effect transistors , 2007 .

[13]  Yang Yang,et al.  Organic thin-film transistors with nanocomposite dielectric gate insulator , 2004 .

[14]  S. Banerjee,et al.  Large-scale synthesis of single-crystalline perovskite nanostructures. , 2003, Journal of the American Chemical Society.

[15]  Raoul Schroeder,et al.  Organic field-effect transistors with ultrathin gate insulator , 2004 .

[16]  N. Mathur,et al.  Multiferroic and magnetoelectric materials , 2006, Nature.

[17]  S. Bauer,et al.  High-mobility pentacene organic field-effect transistors with a high-dielectric-constant fluorinated polymer film gate dielectric , 2005 .

[18]  C. Murray,et al.  Synthesis of monodisperse nanoparticles of barium titanate: toward a generalized strategy of oxide nanoparticle synthesis. , 2001, Journal of the American Chemical Society.

[19]  Longtu Li,et al.  Phase transition and high dielectric constant of bulk dense nanograin barium titanate ceramics , 2006 .

[20]  Jon-Paul Maria,et al.  Alternative dielectrics to silicon dioxide for memory and logic devices , 2000, Nature.

[21]  S. Wada,et al.  Preparation of nm-sized BaTiO3 crystallites by a LTDS method using a highly concentrated aqueous solution , 2001 .

[22]  Raoul Schroeder,et al.  Low‐Voltage, High‐Performance Organic Field‐Effect Transistors with an Ultra‐Thin TiO2 Layer as Gate Insulator , 2005 .

[23]  Nicola A. Spaldin,et al.  Origin of the dielectric dead layer in nanoscale capacitors , 2006, Nature.

[24]  Y. Sakabe,et al.  Low-Operating-Voltage Organic Field-Effect Transistors with Poly-p-Xylylene/High-k Polymer Bilayer Gate Dielectric , 2006 .

[25]  A. Akinwande,et al.  Low-voltage organic transistors and depletion-load inverters with high-K pyrochlore BZN gate dielectric on polymer substrate , 2005, IEEE Transactions on Electron Devices.

[26]  S. Im,et al.  Pentacene thin-film transistors with Al2O3+x gate dielectric films deposited on indium-tin-oxide glass , 2003 .

[27]  Anna C. Balazs,et al.  Nanoparticle Polymer Composites: Where Two Small Worlds Meet , 2006, Science.

[28]  Zhuoying Chen,et al.  Barium titanate nanocrystals and nanocrystal thin films: Synthesis, ferroelectricity, and dielectric properties , 2006 .

[29]  Liyu Li,et al.  Two‐Step Sintering of Ceramics with Constant Grain‐Size, II: BaTiO3 and Ni–Cu–Zn Ferrite , 2006 .

[30]  Jens-Uwe Sommer,et al.  Polymer-nanoparticle films. Entropy and enthalpy at play. , 2007, Nature materials.

[31]  G. Gelinck,et al.  Flexible active-matrix displays and shift registers based on solution-processed organic transistors , 2004, Nature materials.

[32]  C. Dimitrakopoulos,et al.  Organic Thin Film Transistors for Large Area Electronics , 2002 .

[33]  Ute Zschieschang,et al.  Low-voltage organic thin-film transistors with large transconductance , 2007 .

[34]  Alisa Hunt-Lowery,et al.  Copper Compatible Barium Titanate Thin Films for Embedded Passives , 2005 .

[35]  Qing Peng,et al.  A general strategy for nanocrystal synthesis , 2005, Nature.

[36]  Zhuoying Chen,et al.  New nonhydrolytic route to synthesize crystalline BaTiO_3 nanocrystals with surface capping ligands , 2006 .

[37]  S. Studenikin,et al.  Properties of Dielectric BaTiO3 Thin Films Prepared by Spray Pyrolysis , 1998 .

[38]  T. Lewis.  Nanometric dielectrics , 1994 .

[39]  T. Lewis,et al.  Interfaces: nanometric dielectrics , 2005 .

[40]  Robert W. Schwartz,et al.  Chemical Solution Deposition of Perovskite Thin Films , 1997 .

[41]  P. Dutta,et al.  Hydrothermal synthesis of tetragonal barium titanate (BaTiO3) , 1992 .

[42]  Jie Gao,et al.  Dielectric nanocomposites for integral thin film capacitors: materials design, fabrication and integration issues , 2003 .

[43]  Peter J. Hotchkiss,et al.  Phosphonic Acid‐Modified Barium Titanate Polymer Nanocomposites with High Permittivity and Dielectric Strength , 2007 .

[44]  M. Antonietti,et al.  A general soft-chemistry route to perovskites and related materials: synthesis of BaTiO(3), BaZrO(3), and LiNbO(3) nanoparticles. , 2004, Angewandte Chemie.

[45]  E. R. Fisher,et al.  Sol-gel template synthesis and characterization of BaTiO3 and PbTiO3 nanotubes , 2002 .

[46]  R. Ramesh,et al.  Multiferroics: progress and prospects in thin films. , 2007, Nature materials.

[47]  Raoul Schroeder,et al.  High‐Performance Organic Transistors Using Solution‐Processed Nanoparticle‐Filled High‐k Polymer Gate Insulators , 2005 .

[48]  V. Gopalan,et al.  Enhancement of Ferroelectricity in Strained BaTiO3 Thin Films , 2004, Science.

[49]  M. Steigerwald,et al.  Crystal structure and the paraelectric-to-ferroelectric phase transition of nanoscale BaTiO3. , 2008, Journal of the American Chemical Society.

[50]  Hiroshi Matsui,et al.  Room Temperature Synthesis of Ferroelectric Barium Titanate Nanoparticles Using Peptide Nanorings as Templates , 2006, Advanced materials.

[51]  Christopher B. Murray,et al.  Structural diversity in binary nanoparticle superlattices , 2006, Nature.

[52]  M. Antonietti,et al.  Nonaqueous and halide-free route to crystalline BaTiO3, SrTiO3, and (Ba,Sr)TiO3 nanoparticles via a mechanism involving C-C bond formation. , 2004, Journal of the American Chemical Society.

[53]  J. K. Nelson,et al.  Nanocomposite dielectrics—properties and implications , 2005 .

[54]  Ute Zschieschang,et al.  Low-voltage organic transistors with an amorphous molecular gate dielectric , 2004, Nature.

[55]  C. Dimitrakopoulos,et al.  Low-voltage organic transistors on plastic comprising high-dielectric constant gate insulators , 1999, Science.

[56]  Barbara Stadlober,et al.  Low‐Voltage Organic Thin‐Film Transistors with High‐k Nanocomposite Gate Dielectrics for Flexible Electronics and Optothermal Sensors , 2007 .

[57]  V. Bulović,et al.  Tunable threshold voltage and flatband voltage in pentacene field effect transistors , 2006 .