Subgap Density-of-States-Based Amorphous Oxide Thin Film Transistor Simulator (DeAOTS)

The amorphous oxide thin-film transistor (TFT)-oriented simulator [subgap Density of states (DOS)-based Amorphous Oxide TFT Simulator (DeAOTS)] is proposed, implemented, and demonstrated for amorphous indium-gallium-zinc-oxide (a-IGZO) TFTs. It only consists of parameters having their physical meanings and is supplied with concrete techniques for parameter extraction. Among the physical parameters, the acceptor-like DOS gA(E) was experimentally extracted using the multifrequency C-V technique, whereas the donor-like DOS gD(E) and the doping concentration ND were extracted using numerical iterations. The simulation result reproduces the DOS and thin-film-thickness-dependence of dc I-V characteristics very well. Compared with the previously reported a-Si TFT models, the proposed DeAOTS model not only reflects the strong VGS dependence of the effective mobility (μeff) but also clarifies the relations between process-controlled DOS parameters and dc I- V characteristics based on experimentally extracted DOS parameters. Also, it sufficiently takes into account the peculiar situation of amorphous oxide TFTs where the free-carrier charge can be larger than the localized one out of the total induced charge. Moreover, it reproduces the measured electrical characteristics within the wide range of VGS/VDS with a single equation, not distinguishing the operation regions such as the subthreshold, linear, and saturation regimes.

[1]  Sanjiv Sambandan,et al.  Analysis and characterization of self-compensating current programmed a-Si:H active matrix organic light-emitting diode pixel circuits , 2004 .

[2]  J. Wager,et al.  Transparent Electronics , 2003, Science.

[3]  Michael S. Shur,et al.  Physics of amorphous silicon based alloy field‐effect transistors , 1984 .

[4]  Trond Ytterdal,et al.  SPICE Models for Amorphous Silicon and Polysilicon Thin Film Transistors , 1997 .

[5]  A. Nathan,et al.  Electrical Compensation of OLED Luminance Degradation , 2007, IEEE Electron Device Letters.

[6]  E. Lueder,et al.  Modeling of amorphous-silicon thin-film transistors for circuit simulations with SPICE , 1992 .

[7]  Dong Myong Kim,et al.  Extraction of Density of States in Amorphous GaInZnO Thin-Film Transistors by Combining an Optical Charge Pumping and Capacitance–Voltage Characteristics , 2008, IEEE Electron Device Letters.

[8]  Hideo Hosono,et al.  Trap densities in amorphous-InGaZnO4 thin-film transistors , 2008 .

[9]  Yeon-Gon Mo,et al.  Control of threshold voltage in ZnO-based oxide thin film transistors , 2008 .

[10]  Chen-Pang Kung,et al.  P‐14: a‐Si Robust Gate Driver for 7.0‐in. WVGA LCD Panel , 2007 .

[11]  Michael S. Shur,et al.  Threshold voltage, field effect mobility, and gate-to-channel capacitance in polysilicon TFTs , 1996 .

[12]  Satoshi Masuda,et al.  Transparent thin film transistors using ZnO as an active channel layer and their electrical properties , 2003 .

[13]  Jung Woo Kim,et al.  Bottom-Gate Gallium Indium Zinc Oxide Thin-Film Transistor Array for High-Resolution AMOLED Display , 2008, IEEE Electron Device Letters.

[14]  Benjamin J. Norris,et al.  ZnO-based transparent thin-film transistors , 2003 .

[15]  Shiao-Shien Chen,et al.  An analytical a-Si:H TFT DC/capacitance model using an effective temperature approach for deriving a switching time model for an inverter circuit considering deep and tail states , 1994 .

[16]  Jang-Yeon Kwon,et al.  42.2: World's Largest (15‐inch) XGA AMLCD Panel Using IGZO Oxide TFT , 2008 .

[17]  T. Kamiya,et al.  Origins of High Mobility and Low Operation Voltage of Amorphous Oxide TFTs: Electronic Structure, Electron Transport, Defects and Doping* , 2009, Journal of Display Technology.

[18]  Dong Hun Kim,et al.  Thickness Dependence of Gate Dielectric and Active Semiconductor on InGaZnO4 TFT Fabricated on Plastic Substrates , 2008 .

[19]  Dong Myong Kim,et al.  Modeling of amorphous InGaZnO thin-film transistors based on the density of states extracted from the optical response of capacitance-voltage characteristics , 2008 .

[20]  Hideo Hosono,et al.  P‐29: Modeling of Amorphous Oxide Semiconductor Thin Film Transistors and Subgap Density of States , 2008 .

[21]  Peyman Servati,et al.  Above-threshold parameter extraction and modeling for amorphous silicon thin-film transistors , 2003 .

[22]  Michael S. Shur,et al.  A new analytic model for amorphous silicon thin‐film transistors , 1989 .

[23]  Dong Myong Kim,et al.  Density of States-Based DC $I$– $V$ Model of Amorphous Gallium–Indium–Zinc-Oxide Thin-Film Transistors , 2009, IEEE Electron Device Letters.

[24]  H. Ohta,et al.  Carrier transport and electronic structure in amorphous oxide semiconductor, a-InGaZnO4 , 2005 .

[25]  Yongtaek Hong,et al.  Meyer–Neldel Rule and Extraction of Density of States in Amorphous Indium–Gallium–Zinc-Oxide Thin-Film Transistor by Considering Surface Band Bending , 2010 .

[26]  J. Kanicki,et al.  Density of States of a-InGaZnO From Temperature-Dependent Field-Effect Studies , 2009, IEEE Transactions on Electron Devices.

[27]  Dong Myong Kim,et al.  Extraction of Subgap Density of States in Amorphous InGaZnO Thin-Film Transistors by Using Multifrequency Capacitance–Voltage Characteristics , 2010, IEEE Electron Device Letters.

[28]  P. Barquinha,et al.  Gallium–Indium–Zinc-Oxide-Based Thin-Film Transistors: Influence of the Source/Drain Material , 2008, IEEE Transactions on Electron Devices.

[29]  Brian H. Berkeley,et al.  46.1: Invited Paper: Integrated a‐Si:H TFT Gate Driver Circuits on Large Area TFT‐LCDs , 2007 .

[30]  Hideo Hosono,et al.  Subgap states in transparent amorphous oxide semiconductor, In–Ga–Zn–O, observed by bulk sensitive x-ray photoelectron spectroscopy , 2008 .

[31]  H. Ohta,et al.  Thin-Film Transistor Fabricated in Single-Crystalline Transparent Oxide Semiconductor , 2003, Science.

[32]  Shunpei Yamazaki,et al.  P‐9: Numerical Analysis on Temperature Dependence of Characteristics of Amorphous In‐Ga‐Zn‐Oxide TFT , 2009 .

[33]  Jerzy Kanicki,et al.  Two-dimensional numerical simulation of radio frequency sputter amorphous In–Ga–Zn–O thin-film transistors , 2009 .

[35]  H. Ohta,et al.  Room-temperature fabrication of transparent flexible thin-film transistors using amorphous oxide semiconductors , 2004, Nature.

[36]  H. Chu,et al.  P‐8: Effects of Active Thickness in Oxide Semiconductor TFTs , 2009 .