Browsing by Author "Chiou, Ping"

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Amorphous bilayer TiO2-InGaZnO thin film transistors with low drive voltage
(2014-09-01)
Hsu, Hsiao-Hsuan
;
Cheng, Chun-Hu
;
Chiou, Ping
;
Chiu, Yu-Chien
;
Chang, Chun-Yen
This paper describes a high-performance thin-film transistor (TFT) fabricated using TiO2 and InGaZnO semiconducting layers. Favorable transistor characteristics, including a low threshold voltage of 0.45 V, a small subthreshold swing of 174 mV/decade, and a high field effect mobility of 19 cm(2)/V s at a low drive voltage of <2 V, were achieved. This favorable performance mainly resulted from the combined effect of the high-dielectric-constant gate dielectric and the TiO2-InGaZnO active semiconductor bilayer, which reduced the operating voltage, enhanced the device mobility, and improved the transistor gate swing. This TiO2-InGaZnO TFT exhibits great potential for future high-speed and high-resolution display applications. (C) 2014 Elsevier Ltd. All rights reserved.
Amorphous Titanium Oxide Semiconductors on Quasi-Crystal-Like InGaZnO Channels for Thin Film Transistor Applications
(2015-06)
Hsu, Hsiao-Hsuan
;
Chiou, Ping
;
Cheng, Chun-Hu
;
Yen, Shiang-Shiou
;
Tung, Chien-Hung
This paper reports an InGaZnO thin-film transistor with titanium-oxide semiconductor as channel capping layer. Based on the experimental results, the titanium-oxide semiconductor has the function of not only a surface passivation layer to reduce the defect states localized at grain boundaries near source/drain contacts, but also a mobility booster to enhance electric field across channel. Compared to control IGZO TFT, the crystalline IGZO TFTs with titanium-oxide semiconductor exhibits an improved performance of a low drive voltage of <5 V, a low threshold voltage of 1.9 V, a low sub-threshold swing of 244 mV/decade, and a high mobility of 13.7 cm(2)/V s. The simple titanium-oxide capping process have been demonstrated in this work, which provides considerable potential for further display applications requiring a low power operation and a low-temperature fabrication.
Correlation of thermal annealing effect, crystallinity and electrical characteristics in c-axis crystallized InGaZnO thin-film transistors
(2015-09-15)
Hsu, Hsiao-Hsuan
;
Yen, Shiang-Shiou
;
Chiu, Yu-Chien
;
Chiou, Ping
;
Chang, Chun-Yen
A low off-state current of 1.6 x 10(-14) A/mu m and a small subthreshold gate swing of 152 mV/decade were achieved in a novel thin film transistor using a c-axis crystallized InGaZnO semiconductor that could be obtained at a low substrate temperature range of 150 degrees C. From experimental results, we found that the lowered off-state current is mainly attributed to the formation of rich Ga-O bonds to reduce oxygen vacancies, and the c-axis crystallized structure of IGZO to increase the potential barrier on the source side due to the increase of local trap states at the grain boundary. (C) 2015 Elsevier B.V. All rights reserved.
High Mobility Field-Effect Thin Film Transistor Using Room-Temperature High-kappa Gate Dielectrics
(2014-10-01)
Hsu, Hsiao-Hsuan
;
Chang, Chun-Yen
;
Cheng, Chun-Hu
;
Chen, Po-Chun
;
Chiu, Yu-Chien
This paper reports an InGaZnO thin-film transistor (TFT) that involves using fully room-temperature gate dielectrics on a flexible substrate. The wide bandgap dielectrics of HfO2 and Y2O3 exhibited favorable adhesion properties on a flexible substrate compared with conventional low-kappa SiO2 film. Based on the experimental results, the room-temperature IGZO/HfO TFTs demonstrated effective device integrity, and achieve a low drive voltage of < 2 V, a low threshold voltage of 0.46 +/- 006 V, a low sub-threshold swing of 110 +/- 6 mV/decade and an extremely high mobility of 60.2 +/- 32 cm(2)/V s. The excellent performance of this TFT indicated that it demonstrates considerable potential for active-matrix liquid crystal display applications requiring low power consumption and a high driving current.
Improvement of dielectric flexibility and electrical properties of mechanically flexible thin film devices using titanium oxide materials fabricated at a very low temperature of 100 degrees C
(2015-09-15)
Hsu, Hsiao-Hsuan
;
Chiu, Yu-Chien
;
Chiou, Ping
;
Cheng, Chun-Hu
;
電子工程學系及電子研究所
In this works, we investigated a Ti-O material system integrating with InGaZnO thin film transistor. The Ti-O material system with high bond enthalpy can be functionalized by tuning the amount oxygen vacancies to reach the applicable requirements of gate dielectric and channel. Compared to control IGZO TFTs, the flexible TiOx/IGZO TFT reaches a smaller sub-threshold swing (SS) of 125 mV/decade and a higher field effect mobility of 61 cm(2)/V s at a very low operating voltage of 1.5 V. Besides, only slight performance degradation was found after bending test. (C) 2014 Elsevier B.V. All rights reserved.
Structural and electrical characteristics of thin film transistor employing an oriented crystalline InGaZnO channel
(2015-04-01)
Yen, Shiang-Shiou
;
Hsu, Hsiao-Hsuan
;
Chiou, Ping
;
Cheng, Chun-Hu
;
Tung, Chien-Hung
In this study, we investigate the impact of orientated crystalline InGaZnO (IGZO) thin film transistor. To evaluate interface thermodynamic stability of temperature-sensitive IGZO film, the film-structural stabilities of high-and low-indium-content InGaZnO were studied. With increasing annealing temperature up to 700 degrees C, the crystallinity becomes more pronounced while device electrical characteristics are further improved. We find that the apparently reduced off-state current can be attributed to the formation of c-axis-orientated crystalline located at the X-ray diffraction peak of (0, 0, 16). The performance improvements include a very low turn-on voltage close to zero voltage, a small subthreshold swing of 130mV/dec, and a low off-state current of 2.4 x 10(-14)A/mu m at a low operating voltage of 4V. (C) 2015 The Japan Society of Applied Physics
Temperature-Dependent Transfer Characteristics of Low Turn-On Voltage InGaZnO Metal-Oxide Devices With Thin Titanium Oxide Capping Layers
(2015-06)
Hsu, Hsiao-Hsuan
;
Cheng, Chun-Hu
;
Chiou, Ping
;
Chiu, Yu-Chien
;
Yen, Shiang-Shiou
This paper reports an InGaZnO thin-film transistor involving a wide bandgap gate dielectric of ZrO2 and IGZO/TiOx channel stack. According to our experimental results, the IGZO TFT with a thin TiOx channel capping layer shows good device integrity of a low threshold voltage of 0.37 V, a small sub-threshold swing of 77 mV/decade, and a high mobility of 33 cm(2)/V.s under a low drive voltage of < 2 V. We also demonstrate that the significantly improved electrical property is mainly contributed by the enhanced channel electric field after TiOx capping, associated with maximizing charge accumulated capability. The favorable high-temperature transfer characteristics are also obtained in IGZO/TiOx TFT, indicating a weak Fermi-level pinning in IGZO/TiOx channel structure. With the operating temperature increasing further, the thermal activated effect shall dominate IGZO channel property beyond percolation conduction.