International Workshop on Transparent Amorphous Oxide Semiconductors (TAOS 2010) †
News †
Opening Speech †
- Kenichi Iga, President of Tokyo Institute of Technology
- Hideo Hosono, IRI&FRC&MSL, Tokyo Institute of Technology
Keynote Speech †
- Jun H. Souk, Former Vice President, Senior Advisor of Samsung Electronics, Korea
Evolution of TFTs for the Advancement in Next Generation Display
Jun H. Souk
Samsung Electronics
The flat panel displays are evolving toward larger screen and higher
resolution. Futhermore, high frame rate and 3D display are becoming
commodity products. To achieve this next generation FPDs, a practical
semi-conductor material with high speed switching capability and reliability
is in great need. We review the status and competitiveness of a-Si, micro
crystalline Si, LTPS and oxide TFT and the development effort in display
industry today. Also, the performance criteria for high speed TFTs to drive
next generation displays are described.
Invited Talks †
- Keita Arihara, Dai Nippon Printing, Japan
Fabrication of Flexible 4.7-inch QVGA AMOLED Panel Driven
by In-Ga-Zn-Oxide TFTs with Flexible Color Filter
Keita Arihara, Masataka Kano, Osamu Iwata, Katsuyuki Motai,
Yasunori Naitou, Masaru Kadowaki, Hiroyoshi Nakajima,
Tatsuya Tsuboi, Chiaki Kato, Yoshihiro Kishimoto, and Hiroki Maeda
Research and Development Center, Dai Nippon Printing Co., Ltd.
We have developed a flexible active matrix organic light-emitting
diode (OLED) display driven by amorphous In-Ga-Zn-Oxide thin film
transistors fabricated onto stainless steel substrates.
A 320×240×RGB 4.7-inch panel was achieved by using white-OLEDs
and a flexible color filter. Also, preferable full color moving
images were demonstrated at the frame frequency of 60 Hz. Detailed
discussion will be presented at a conference site.
- Greg S. Herman , Oregon State Univ., USA
Printed Transparent Amorphous Oxide Semiconductors
Chih-hung Chang, Seung-Yeol Han and Gregory S. Herman
Oregon State University
School of Chemical, Biological, and Environmental Engineering
There has been tremendous interest in the utilization of
Transparent Amorphous Oxide Semiconductors (TAOS) for a variety of
applications including electronic paper, LCD, and OLED.
We have recently developed chemistries for high-performance,
solution-processed TAOS materials, which is generally applicable to
a variety of printing technologies. The precursor chemistries are
stable, form uniform continuous films, and we have demonstrated
field effect mobilities of ~30 cm2/Vs for inkjet printed TAOS TFTs.
- Kee-Joo Chang, KAIST, Korea
Electronic and defect properties of oxide semiconductors
Byunki Ryu, Eun-Ae Choi, Junhyeok Bang, Woo-Jin Lee,* and Kee Joo Chang
Department of Physics, Korea Advanced Institute of Science and Technology
*Korea Research Institute of Standard and Science
We present the results of first-principles density functional
calculations for the defect properties of O-vacancy and hydrogen
in oxide semiconductors, such as ZnO and InGaZnO. The electronic
structure of O-vacancy at the interface between ZnO and HfO2 is
also examined and the role of defects in device performance is discussed.
- Antonio Facchetti, Northwestern Univ., USA
Amorphous Sn-In-O and Zn-Ga-In-O semiconductor films for
transistor applications
Antonio Facchetti, Myung-Gil Kim, Hyun Sung Kim, Young-Geun Ha,
Jiaquing He, Mercouri G. Kanatzidis, Antonio Facchetti, and Tobin J. Marks
Department of Chemistry and Materials Research Center Northwestern University
In this presentation I will discuss our latest results in developing
amorphous Sn-In-O and Zn-Ga-In-O formulations in which the corresponding
films can be annealed at temperatures < 250 ºC. For instance,
solution-processed amorphous tin-doped indium oxide (ITO) films for TFT
fabrication at temperatures <250 °C can be achieved by controlling film
precursor solution In+3 vs. Sn+4 molar ratio resulting in electron mobilities
> 2 cm2 V−1s−1 and Ion:Ioff > 10^4 for TFTs using SiO2 as the gate dielectric.
Furthermore, we demonstrate that hybrid integration of solution-processed
ITO semiconductor films SAND enables m ~ 20 cm2 V−1s−1.
- Ming-Chin Hung, AU Optronics, Taiwan
Process Development and Reliability Study of a-IGZO Thin Film Transistor
Ming-Chin Hung, Wei-Ting Lin, Jiun-Jye Chang, Po-Lun Chen
Advanced Display Research Div., Advanced Technology Research Center
Chen-Yi Wu, Chi-Jui Lin, Hao-Lin Chiu, Chun-Yao Huang
Array Device Tech. Dept.
Yih-Chyun Kao
Array / CF Process Development Div.
Since a-IGZO is vulnerable to general wet etchants or dry etching process,
the bottom gate and coplanar device structure is developed and evaluated.
Through customized wet etchants with etching selectivity greater than 100,
the back-channel etch (BCE) device is also made feasible. In addition,
NBTS as well as PBTS are both done to study the instability of a-IGZO TFT
and a degradation mechanism is provided herein to elucidate
the stability issue.
- Hsing-Hung Hsieh, AU Optronics, Taiwan
IGZO Thin-Film Transistors for AMOLED applications
Hsing-Hung Hsieh*, Tsung-Ting Tsai, Chin-Yu Chang,
Hsiao-Han Wang, Jung-Yen Huang, Shih-Feng Hsu, Yuan-Chun Wu,
Tze-Chien Tsai, Ching-Sang Chuang, Lee-Hsun Chang, and Yu-Hsin Lin
OLED Technology Div., AU Optronics Corp.
We will show that the indium-gallium-zinc-oxide (IGZO)
can be a good and strong alternative candidate for AMOLED
backplane. The electrical characteristics, stability and
reliability of IGZO TFTs will be particularly investigated.
Further, various types of IGZO TFT AMOLED displays have been
fabricated and shown superior performance compared to most
other AMOLED backplane technologies.
- Manabu Ito, Toppan Printing Co., Ltd., Japan
Application of Transparent Amorphous Oxide Semiconductor TFT
to Electronic Paper
Manabu Ito, Chihiro Miyazaki, Noriaki Ikeda, Mamoru Ishizaki,
and Yoshiko Ugajin
Technical Research Institute, Toppan Printing Co., Ltd.
Electronic paper has been attracted a lot of attention as
a next generation media. Taking advantage of the low process
temperature, transparency and applicability for the printing
process of TAOS, applications of TAOS TFT to electronic paper
are demonstrated.
- Warren Jackson, HP, USA
Metastability in Multicomponent Oxides
W. Jackson, R. Hoffman, B. Yeh, T. Koch
Hewlett Packard
Metastability in multicomponent oxide (MCO) based transistors is
a complex process that is critical for wide spread adoption of MCO
technology. The time and temperature dependence of the threshold voltage
metastability in MCO devices for various gate dielectrics, passivation layers,
and annealing protocols has been measured. In this talk the metastability
will be compared with amorphous silicon. Unlike amorphous silicon,
the threshold voltage metastability has both short and long time components
and nearly always shifts to negative voltages eventually. Some aspects of
the metastability are clearly related to oxygen vacancies. Various possible
metastability processes will be discussed.
- Jae Kyeong Jeong, Inha Univ., Korea
Study on the stability degradation mechanism of oxide
thin film transistors under the bias-thermal stress condition
Jae Kyeong Jeong1, Yeon-Gon Mo,2 Min Ki Ryu3, and Shinhyuk Yang3
1 Department of Materials Science and Engineering, Inha University
2 R&D Center, Samsung Mobile Display
3 Tranparent Electronics Team, ETRI
We will present the plausible degradation mechanism of the oxide TFTs
under the gate bias stress and thermal stress. After introducing
the dynamical ambient model, the correlation between gate bias instability
and temperature instability will be investigated. Finally, the strategies
for improving the stability of oxide TFTs will be suggested based on
the proposed mechanism framework.
- Jerzy Kanicki, Univ. Michigan, USA
a-IGZO Density of States: Photo-Field Effect and
Temperature Dependence Studies
T.C. Fung, C. Chen and J. Kanicki
Department of EECS, University of Michigan
To study the a-InGaZnO (a-IGZO) electronic properties
the photo-field and temperature effects on a-InGaZnO (a-IGZO)
thin-film transistor electrical properties were investigated.
More specifically a-IGZO mid-gap density-of-states values were
extracted from these studies [1], [2]. Obtained values are
compared to DOS extracted for a-Si:H TFT using the same approach.
[1] T.-C. Fung et al., J. of Information Display, vol. 9, pp. 21-29, 2008.
[2] C. Chen et al., IEEE Transactions on Electron Devices, vol. 56,
pp. 1177-1183, 2009.
- Hideya Kumomi, Canon Inc., Japan
Materials and Devices of Transparent Amorphous Oxide Semiconductors
H. Kumomi, S. Yaginuma, H. Omura, A. Goyal, A. Sato, M. Watanabe,
M. Shimada, N. Kaji, K. Takahashi, M. Ofuji, T. Watanabe, N. Itagaki,
H. Shimizu, K. Abe, Y. Tateishi, H. Yabuta, T. Iwasaki, R. Hayashi,
T. Aiba, and M. Sano
Canon Inc.
We present progress in exploration of new material composition
in transparent amorphous oxide semiconductors (TAOS)
for thin-film transistors (TFTs), impurity effects in TAOS materials,
and characteristics and stability of TFTs having a few device structures
including coplanar-homojunction type TFTs.
- Woo-Geun Lee, Samsung Electronics, Korea
Investigation on the long term stability of LCD panel
with GIZO oxide TFTs
Woo-Geun Lee, Kap-Soo Youn, Kyung-Jae Chung, Dong-Hoon Lee,
Hye-Young Ryu, Young-Joo Choi, Jun-Hyung Souk, Jae-Woo Park,
Sung-Tae Shin
Samsung Electronics Co., Ltd.
Transparent Amorphous Oxide Semiconductor (TAOS) TFTs are
very promising candidate for the switching devices of next
generation display. The advantages of oxide semiconductor with
high mobility and amorphous phase are very attractive to large
size ultra high definition LCD panel. We have fabricated on
the 17” SXGA AMLCD panel with GIZO TFTs and characterized
the long-term stability of the panel.
- Mitsuru Nakata, NEC Corp., Japan
Low-Temperature Fabrication of Amorphous InGaZnO4
Thin-Film Transistors Utilizing Excimer Laser
Mitsuru Nakata1, Kazushige Takechi1, Shinya Yamaguchi1,
Eisuke Tokumitsu2, Hiroshi Tanabe3, and Setsuo Kaneko3,4
1 Technology Research Association for Advanced Display Materials (TRADIM)
2 Tokyo Institute of Technology
3 NEC LCD Technologies, Ltd.
4 NEC Corporation
We have developed an annealing method for InGaZnO4 (IGZO)
by utilizing excimer laser to obtain good transfer characteristics
in IGZO thin-film transistors on plastic substrates.
Because of the extremely short pulse width of the laser (25 ns),
it is possible to selectively increase the temperature of
the IGZO with negligible thermal damage to the plastic substrate.
- Kenji Nomura, Tokyo Tech, Japan
Improvement of device characteristic and stability of
a-In-Ga-Zn-O based TFTs.
Kenji Nomura1, Toshio Kamiya1,2, Masahiro Hirano1 and Hideo Hosono1,2
1 Transparent Electro-Active Materials Project, ERATO-SORST, JST
2 Materials and Structures Laboratory, Tokyo Institute of Technology
We have investigated the role of thermal annealing in a-In-Ga-Zn-O
(a-IGZO) and have found that wet O2 thermal annealing is more effective
to improve device characteristics including their uniformity than
dry O2 annealing. We have also examined the stability under
constant current stress for the unannealed and annealed a-IGZO-TFTs.
The detail and the origin of TFT instability will be discussed
at the conferences.
- Chul-Hong Park, Pusan Natl. Univ., Korea
First-principles study of microscopic properties of
O-deficient amorphous InGaZnO4
I.-J. Kang and C. H. Park
Research Center for Dielectrics and Advanced Matter Physics,
Pusan National University, Pusan 609-735, South Korea
Through the first-principles calculations, we investigated
the electronic structures of the O-deficient amorphous InGaZnO
and their microscopic structures through the molecular dynamics
calculations. We also examine the cation-rich amorphous oxides
and the driven sub-gap states. Finally we will discuss the role
of In on the electronic structure of O-deficient amorphous oxides.
- Hyun Sik Seo, LG Display, Korea
Highly stable a-IGZO TFT with Ti etch stopper and in-situ formation of
TiOx passivation layer for active matrix display
Hyun-Sik Seo, Jong-Uk Bae, Dae-Won Kim, Chang Il Ryoo, Im-Kuk Kang,
Soon-Young Min, Yong-Yub Kim, Joon-Soo Han, Chang-Dong Kim, and YongKee Hwang
LG Display R&D Center
Amorphous-IGZO TFTs including newly developed high stable and simple TiOx
passivation layer have been fabricated. Molybdenum/titanium ( Mo/Ti ) is
used as a S/D electrode where Ti plays a role as an ohmic contact with a-IGZO,
etch stopper layer, and passivation layer by forming of TiOx. It is found
that the formation of TiOx is proportional to the oxygen plasma treatment
time and measured that Ion / Ioff ratio, s-factor, and mobility are higher
than 10^7, 0.2 V dec.-1, and 9 cm2 V-1 sec-1, respectively.
- Koichi Shimakawa, Gifu Univ., Japan
Anomalous optical conductivity in exotic metals
K. Shimakawa
Department of Electrical and Electronic Engineering, Gifu University
Optical conductivities near infrared region in some exotic metals
do not follow the classical Drude law. We discuss an origin of
the anomalous free carrier absorption in metallic states of
some oxides, polymers, high-Tc superconductors etc. Coexistence of
“localized” and “extended” natures of carriers may produce anomalies
in free carrier absorption.
- Akitsugu Hatano, Sharp Coop., Japan
Amorphous In-Ga-Zn-O TFT-LCDs with high reliability
Masahiko Suzuki, Yoshifumi Ohta, Yoshimasa Chikama, Takeshi Hara,
Yuuji Mizuno, Michiko Takei, Okifumi Nakagawa, Yoshiyuki Harumoto,
Akitsugu Hatano*, Yoshitaka Yamamoto
SHARP CORPORATION
We have developed amorphous In-Ga-Zn-O (IGZO) TFTs with
the inverted-staggered structure. The TFT performance is good enough
for TFT-LCDs. In addition, we evaluate the TFT reliability.
The reliability of IGZO TFT-LCDs is also evaluated under
high temperature ambient. In this report, we discuss our IGZO TFT
process, performance and reliability.
- Hiroyuki Uchiyama, Hitachi, Ltd., Japan
Low-Voltage Operating Amorphous-IGZO TFTs
Hiroyuki Uchiyama1, Tetsufumi Kawamura1, Hironori Wakana1,
Shinichi Saito1, and Toshiyuki Mine2
1 Central Research Laboratory, Hitachi Ltd.,
and SORST, Japan Science and Technology
2 Central Research Laboratory, Hitachi Ltd.
We fabricated fully-depleted type a-IGZO TFTs
which were achieved by designing the channel layer thickness
and carrier density sufficiently small. The subthreshold slope
smaller than 100 mV/dec and the on/off ratio greater than 1×10^7
were achieved for 1.5-V operation.
- Yukiharu Uraoka, NAIST, Japan
Realibility of amorphous IGZO Thin Film Transistor
Y.Uraoka, Mami Fujii and M.Horita
Nara Institute of Science and Technology
Amorphous IGZO thin film is promising material for an active channel
for next generation displays, such as OLED or flexible displays.
In order to realize these displays, reliability is one of
the serious problems in Amorphous IGZO thin film transistors.
We evaluated the reliability against the electrical stress and
discussed the degradation mechanism comparing with that in the silicon TFT.
- Chung-Chih Wu, Natl. Taiwan Univ., Taiwan
Highly Flexible a-IGZO TFTs Adopting Composite Electrodes and
Transparent Polyimide Substrates
Chung-Chih Wu1, Chih-Wei Chien1, Hsing-Hung Hsieh1, Chang-Yu Lin2,
Yung-Hui Yeh2, Chyi-Ming Leu3, Tzong-Ming Lee3
1 Graduate Institute of Electronics Engineering,
Graduate Institute of Photonics and Optoelectronics,
and Department of Electrical Engineering
2 Electronics and Optoelectronics Research Laboratories (EOL),
Industrial Technology Research Institute
3 Material and Chemical Research Laboratories (MCL),
Industrial Technology Research Institute
In this presentation, we will report highly flexible oxide TFTs
with decent mobility and mechanical bending capability on
colorless/transparent PI substrates, fabricated by directly c
oating PI on the glass carrier, batch lithographic/etching processes,
de-bonding after TFT fabrication, and particularly adoption of
a composite electrodes for TFTs.
Closing remarks †
- Toshio Kamiya, Tokyo Tech, Japan
How to join? †
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Registration fee: Free
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