Browsing by Author "Tung, Chien-Hung"

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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.
Gettering Effect Induced by Oxygen-Deficient Titanium Oxide in InZnO and InGaZnO Channel Systems for Low-Power Display Applications
(2016-03)
Yen, Shiang-Shiou
;
Chiu, Yu-Chien
;
Cheng, Chun-Hu
;
Chen, Po-Chun
;
Yeh, Yu-Chen
This paper reported the IGZO and IZO thin-film transistor (TFT) with titanium-oxide semiconductor as channel capping layer. After the TiOx Gettering process, the oxygen vacancies in IGZO channel were successfully modified to maximize the carrier concentration and device mobility. The superior transfer characteristics included a low sub-threshold swing of 79 mV/decade, a very high mobility of 68 cm(2)/V.s, and good on/off-current ratio of 5.61 x 10(6). However, the IZO channel with nano-crystallized grains and without Ga atom doping showed unfavorable transistor characteristics. In addition to apparently degraded transfer properties, the spontaneously oxidized TiOx capping layer also lead to an increase of channel parasitic resistance that limits the output driving current. Therefore, we believe that the existence of Ga-O bonds among IGZO channel would be helpful to stabilize oxygen diffusion behavior and electric structure during Gettering process.
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.