Amorphous In–Ga–Zn–O Dual-Gate TFTs: Current–Voltage Characteristics and Electrical Stress Instabilities

We studied the electrical characteristics and electrical stress instabilities of amorphous In-Ga-Zn-O (-IGZO) dual-gate thin-film-transistors (DG TFTs). A threshold voltage of the bottom-gate (BG)-driven -IGZO DG TFTs showed a linear dependence on the top-gate (TG) voltage. The slope of this dependence is associated with the ratio of the TG to BG insulator capacitance. The BG-driven DG TFT showed linear field-effect mobility comparable to that of a single-gate (SG) TFT without the TG electrode and a smaller saturation field-effect mobility and a larger subthreshold swing in comparison to the SG TFT. These characteristics were explained by the BG-driven DG TFT model formulated by taking the TG bias effect into account. The TG interface showed worse stability under an electric bias stress in comparison to the BG interface. It was also found that a negative voltage applied to the TG improved the stability of the DG TFT under a constant-current stress. These observations suggest that the BG-driven -IGZO DG TFTs with the appropriate negative TG voltage applied can simultaneously show both normally off characteristics and higher stability than the SG TFTs.

[1]  K. Abe,et al.  Electrical Properties and Stability of Dual-Gate Coplanar Homojunction DC Sputtered Amorphous Indium–Gallium–Zinc–Oxide Thin-Film Transistors and Its Application to AM-OLEDs , 2011, IEEE Transactions on Electron Devices.

[2]  T. Kamiya,et al.  Highly stable amorphous In-Ga-Zn-O thin-film transistors produced by eliminating deep subgap defects , 2011 .

[3]  T. Kamiya,et al.  Electronic Structure and Photovoltaic Properties of n-Type Amorphous In-Ga-Zn-O and p-Type Single Crystal Si Heterojunctions , 2011 .

[4]  M. Hirano,et al.  Simple Analytical Model of On Operation of Amorphous In–Ga–Zn–O Thin-Film Transistors , 2011, IEEE Transactions on Electron Devices.

[5]  Jang-Yeon Kwon,et al.  Highly Stable Double-Gate Ga–In–Zn–O Thin-Film Transistor , 2010, IEEE Electron Device Letters.

[6]  Jang-Yeon Kwon,et al.  Characteristics of Double-Gate Ga–In–Zn–O Thin-Film Transistor , 2010, IEEE Electron Device Letters.

[7]  K. Takahashi,et al.  Materials, Devices, and Circuits of Transparent Amorphous-Oxide Semiconductor , 2009, Journal of Display Technology.

[8]  M. Nakata,et al.  Dual-Gate Characteristics of Amorphous $ \hbox{InGaZnO}_{4}$ Thin-Film Transistors as Compared to Those of Hydrogenated Amorphous Silicon Thin-Film Transistors , 2009, IEEE Transactions on Electron Devices.

[9]  Hideo Hosono,et al.  Origins of threshold voltage shifts in room-temperature deposited and annealed a-In–Ga–Zn–O thin-film transistors , 2009 .

[10]  K. Abe,et al.  a‐InGaZnO thin‐film transistors for AMOLEDs: Electrical stability and pixel‐circuit simulation , 2009 .

[11]  Hideo Hosono,et al.  Amorphous In–Ga–Zn–O coplanar homojunction thin-film transistor , 2009 .

[12]  J. Myoung,et al.  Dual-gate InGaZnO thin-film transistors with organic polymer as a dielectric layer , 2009 .

[13]  Sung-Min Yoon,et al.  Analytical Modeling of IGZO Thin-Film Transistors Based on the Exponential Distribution of Deep and Tail States , 2009 .

[14]  Huaxiang Yin,et al.  Double gate GaInZnO thin film transistors , 2008 .

[15]  Hideo Hosono,et al.  Modeling of amorphous InGaZnO4 thin film transistors and their subgap density of states , 2008 .

[16]  Hideo Hosono,et al.  Circuits using uniform TFTs based on amorphous In‐Ga‐Zn‐O , 2007 .

[17]  T. Kamiya,et al.  High-mobility thin-film transistor with amorphous InGaZnO4 channel fabricated by room temperature rf-magnetron sputtering , 2006 .

[18]  Hideo Hosono,et al.  Ionic amorphous oxide semiconductors: Material design, carrier transport, and device application , 2006 .

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

[20]  Hyung-Kyu Lim,et al.  Threshold voltage of thin-film Silicon-on-insulator (SOI) MOSFET's , 1983, IEEE Transactions on Electron Devices.

[21]  Hideo Hosono,et al.  Material characteristics and applications of transparent amorphous oxide semiconductors , 2010 .