Browsing by Author "Yen, Kuo-Hsi"

Now showing 1 - 10 of 10

Effects of Ar/N-2 flow ratio on sputtered-AlN film and its application to low-voltage organic thin-film transistors
(2006-10-01)
Zan, Hsiao-Wen
;
Yen, Kuo-Hsi
;
Liu, Pu-Kuan
;
Ku, Kuo-Hsin
;
Chen, Chien-Hsun
In this work, we applied a low-temperature (150 degrees) alumina nitride (AIN) film as the gate dielectric in organic thin-film transistors (OTFTs). It was found that the Poole-Frenkel-type leakage can be suppressed by increasing the nitrogen gas ratio in the deposition process. The thin and low-leakage AIN dielectric was characterized and then utilized in pentacene-based OTFTs. The proposed AIN dielectric greatly lowers the OTFT operating voltage (< 5 V). A low threshold voltage (-1.5 V), a low subthreshold swing (104 mV/decade), and a high on/off current ratio (> 10(5)) were also obtained for the AIN-OTFTs.
Electric field simulation of the TBC-OTFTs with meshed source electrodes
(2007-01-01)
Zan, Hsiao-Wen
;
Wang, Kuang-Ming
;
Yen, Kuo-Hsi
;
光電工程學系
;
Department of Photonics
It was found that Fowler-Nordheim tunneling effect is the dominant mechanism for vertical channel organic thin film transistors with ultra short channel. In order to improve the device saturation characteristics and to lower down the leakage current, a new device structure with meshed source electrodes was introduced. By using Silvaco TCAD simulation, obvious fringing field effect was observed when the meshed source structure was used. The fringing field would suppress Fowler-Nordheim tunneling effect and improve the gate control ability. As a result, lower leakage current and better saturation characteristics could be obtained.
Electrical Properties of Metal-Silicon Nitride-Hydrogenated Amorphous Silicon Capacitor Elucidated Using Admittance Spectroscopy
(2008-12-01)
Hsieh, Ming-Ta
;
Chen, Jenn-Fang
;
Yen, Kuo-Hsi
;
Zan, Hsiao-Wen
;
Chang, Chan-Ching
Detailed admittance spectroscopy was performed on a metal-silicon nitride-hydrogenated amorphous silicon (MIAS) structure. On the basis of the properties of hydrogenated amorphous silicon (a-Si:H), three simplified equivalent circuit models under various operating conditions (accumulation, depletion and full depletion) are presented along with an alternative direct measurement method at room temperature. Admittance spectroscopy shows that the interface states density between silicon nitride (SiN(x)) and a-Si:H can be determined from the depletion equivalent circuit model. The resisivity and activation energy of a-Si:H can also be obtained using the accumulation and depletion equivalent circuit models. These models can be employed easily to monitor the fabrication parameters of thin-films transistors (TFTs) and to accurately and directly obtain the capacitance model parameters of TFTs. [DOI: 10.1143/JJAP.47.8714]
High photoresponsivity of pentacene-based organic thin-film transistors with UV-treated PMMA dielectrics
(2008)
Zan, Hsiao-Wen
;
Yen, Kuo-Hsi
;
光電工程學系
;
顯示科技研究所
;
Department of Photonics
A simple UV-treatment process for poly(methyl methacrylate) (PMMA) dielectric is proposed to enhance photoresponsivity of pentacene-based organic thin-film transistors. The UV treatment creates excess negatively charged sites on the PMMA dielectric, which makes the device exhibit a large photoinduced current and prolongs persistent conductance recovery. In order to describe time-dependent photoinduced current, double-time constant equations are proposed. Based on time-constant fittings, slow-varied responses are found to be influenced by the UV treatment. The rapid-varied response is independent of gate bias and UV treatment. A plausible model for spatial carrier distribution is discussed and proposed to describe this observed phenomenon.
Low-voltage organic thin film transistors with hydrophobic aluminum nitride film as gate insulator
(2007-08-01)
Zan, Hsiao-Wen
;
Yen, Kuo-Hsi
;
Liu, Pu-Kuan
;
Ku, Kuo-Hsin
;
Chen, Chien-Hsun
This paper reports on the low-voltage (< 5 V) pentacene-based organic thin film transistors (OTFTs) with a hydrophobic aluminum nitride (AlN) gate-dielectric. In this work, a thin (about 50 nm), smooth (roughness about 0.18 nm) and low-leakage AlN gate dielectric is obtained and characterized. The AlN film is hydrophobic and the surface free energy is similar to the organic or the polymer films. The demonstrated AlN-OTFTs were operated at a low-voltage (3-5 V). A low-threshold voltage (-2V) and an extremely low-subthreshold swing (similar to 170 mV/dec) were also obtained. Under low-voltage operating conditions, the on/off current ratio exceeded 106, and the field effect mobility was mobility was 1.67 cm(2)/V s.(c) 2006 Elsevier B.V. All rights reserved.
Organic thin-film transistors with AIN film as a gate-insulator by RFIICP sputtering
(2005-01-01)
Yen, Kuo-Hsi
;
Zan, Hsiao-Wen
;
Ko, Chueh-Ping
;
Liu, Pu-Kuan
;
Chang, Tzu-Yueh
We firstly fabricated the organic thin-film transistors with sputtered-AlN film as the gate insulator. The AlN film was deposited by the RF-ICP (Induced Couple Plasma) sputtering. The demonstrated pentacene based TFTs had on/off current ratio around 4 and mobility around 5x10(-4) cm(2)/Vs without any surface treatment and pentacene purification. All optimized conditions for this new proposed device were under processing.
Pentacene patterning on aluminum nitride by water dipping
(2008)
Zan, Hsiao-Wen
;
Chou, Cheng-Wei
;
Wang, Chung-Hwa
;
Yen, Kuo-Hsi
;
Hwang, Jenn-Chang
This study reports a pentacene patterning method that can be combined with conventional lithography to pattern pentacene film. The aluminum nitride (AlN) surface was patterned using a conventional photolithography process and then treated with oxygen (O(2)) plasma on uncovered AlN to modify surface polarity. Following pentacene deposition, the sample was dipped in water to remove pentacene from the O(2) plasma-treated area. The O(2) plasma-treated AlN surface was analyzed using X-ray photoelectron spectroscopy (XPS) before pentacene deposition. The polar surface energy changed from 13.2 to 114.4 mJ/m(2) when the AlN surface was treated with O(2) plasma at 100 W for 10 min. The polar surface energy was attributed to the increase of Al-O bonds on the surface based on XPS measurements. The intrusion energy of water was enhanced from 34.5 to 140.4 mJ/m(2) due to the polar surface energy induced by the O(2) plasma treatment. The enhancement of water intrusion energy and the polar surface energy explains the water-removable pentacene patterning mechanism. (C) 2008 The Electrochemical Society.
Study the electrical properties of non-crystalline semiconductor by admittance spectroscopy
(2007)
Hsieh, Ming-Ta
;
Chang, Chan-Ching
;
Chen, Jenn-Fang
;
Zan, Hsiao-Wen
;
Yen, Kuo-Hsi
We developed three types of equivalent circuit model to investigate the electrical properties of non-crystalline semiconductor. From the equivalent circuit models, parameters of non-crystalline semiconductor can be easily obtained by admittance spectroscopy. This method also can be utilized in the optimization of device process as well.
Surface energy and adhesion energy of solution-based patterning in organic thin film transistors
(2008-02-29)
Zan, Hsiao Wen
;
Chou, Cheng-Wei
;
Yen, Kuo-Hsi
;
光電工程學系
;
顯示科技研究所
This study elucidates the patterning of pentacene by adjusting its surface energy. The surface energy was modified by self-assembled monolayer treatment and exposure to ultra-violet (UV) light through a quartz-glass mask. Then, following pentacene deposition, dipping in water was used to remove pentacene from the UV-exposed area. The adhesion energy and the intrusion energy were analyzed to determine the mechanism of this patterning process. The variation of the intrusion energy with the surface energy was found to be the main issue in pentacene patterning. The characteristics of pentacene-organic thin film transistors were also measured to confirm the proposed method. (C) 2007 Elsevier B.V. All rights reserved.
Vertical-channel organic thin-film transistors with meshed electrode and low leakage current
(2007-06-01)
Zan, Hsiao-Wen
;
Yen, Kuo-Hsi
;
光電工程學系
;
顯示科技研究所
;
Department of Photonics
In this study, we have successfully fabricated vertical-channel organic thin-film transistors with a channel length smaller than 100nm. It is found that Fowler-Nordheim tunneling is the dominant mechanism determining the ultra short-channel device behavior. To improve the gate control capability, a meshed source electrode pad had been used. This significantly lowers the gate and drain driving voltages (<10V), improves the saturation characteristics and reduces the leakage current. The improvement may be due to the fringing field around the source electrode, which suppresses the tunneling effect.