Browsing by Author "Wang, YW"

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Influence of measuring environment on the electrical characteristics of pentacene-based thin film transistors
(2004-11-22)
Wang, YW
;
Cheng, HL
;
Wang, YK
;
Hu, TH
;
Ho, JC
This work concerns the electrical properties and carrier transport behavior of polycrystalline pentacene-based thin film transistors (TFTs) in air and high-vacuum environments. The transistor in a high vacuum outperforms that in air. The dependence of the field-effect mobility on the gate voltage and the drain voltage is considered. A potential barrier model is applied to estimate the trap density of the pentacene transistor. The determined trap density at the grain boundaries of the pentacene film in air exceeds that in a high vacuum. These results show that the increased trap concentration at the grain boundaries in ambient air limits carrier transport. (C) 2004 Elsevier B.V. All rights reserved.
Pentacene-based thin film transistors used to drive a twist-nematic liquid crystal display
(2005-11-22)
Wang, YW
;
Cheng, HL
;
Wang, YK
;
Hu, TH
;
Ho, JC
The study addresses the factors of influence on the active matrix display that is driven by pentacene-based organic thin-film transistors (TFTs). The atmosphere and humidity conditions were found to seriously affect the performance of organic TFTs. An appropriate encapsulation layer was added to protect the organic TFTs from external damage. Organic TFTs reliability, the illumination effect and device uniformity, were also considered in the context of display application. Finally, a monochrome 3 inch 64 x 128 active-matrix twist-nematic liquid crystal display (LCD) was fabricated. The display is capable of showing video images with a refresh rate of 20 Hz. Obtained results reveal the potential of organic TFTs for active-matrix LCD technology. (c) 2005 Elsevier B.V All rights reserved.
Sol-gel-derived Zn((1-x))Mg(x)O thin films used as active channel layer of thin-film transistors
(2005-07-01)
Lee, JH
;
Lin, P
;
Lee, CC
;
Ho, JC
;
Wang, YW
Sol-gel derived n-type Zn((1-x))Mg(x)O (x = 0-0.45) thin films and thin-film transistors (TFTs) with active channel layers made of the films were investigated. The films were prepared at 500 degrees C. The effects of Mg doping on the crystallinity, optical transparency, grain size, and charge-carrier concentration (n) of the films were examined. The Fermi level of the films, as derived from the temperature dependence of n, was similar to 0.12eV below the conduction band. The donor concentration and donor level (E(d)) were derived by a curve fitting method based on the electrical neutrality condition. Ed was found to be similar to 0.3 eV below the conduction band. The composition dependence of the TFT output characteristics was interpreted and correlated to the width of the depletion region adjacent to the grain boundaries. When the grains were almost depleted at x = 0.2, the TFT showed an enhancement mode and an on/off ratio of 10(6).
Sol-gel-derived Zn(1-x)MgxO thin films used as active channel layer of thin-film transistors
(2005-07-01)
Lee, JH
;
Lin, P
;
Lee, CC
;
Ho, JC
;
Wang, YW
Sol-gel derived n-type Zn(1-x)MgxO (x = 0-0.45) thin films and thin-film transistors (TFTs) with active channel layers made of the films were investigated. The films were prepared at 500 degrees C. The effects of Mg doping on the crystallinity, optical transparency, grain size, and charge-carrier concentration (n) of the films were examined. The Fermi level of the films, as derived from the temperature dependence of n, was similar to 0.12eV below the conduction band. The donor concentration and donor level (E-d) were derived by a curve fitting method based on the electrical neutrality condition. Ed was found to be similar to 0.3 eV below the conduction band. The composition dependence of the TFT output characteristics was interpreted and correlated to the width of the depletion region adjacent to the grain boundaries. When the grains were almost depleted at x = 0.2, the TFT showed an enhancement mode and an on/off ratio of 10(6).