Browsing by Author "Yang, Chuan-Yi"

Now showing 1 - 10 of 10

Ambipolar transport behavior in In(2)O(3)/pentacene hybrid heterostructure and their complementary circuits
(2008-07-21)
Dhananjay
;
Ou, Chun-Wei
;
Yang, Chuan-Yi
;
Wu, Meng-Chyi
;
Chu, Chih-Wei
In this Letter, ambipolar transport properties of a bilayer of In(2)O(3) and a pentacene heterostructure have been realized. While In(2)O(3) thin film transistors exhibited a n-channel behavior, pentacene presumed p-channel characteristics on bare SiO(2)/p-Si substrates. However, when a bilayer of In(2)O(3)/pentacene was realized on the gate dielectrics, the hybrid structure exhibited both n- and p-channel conductions, depicting an ambipolar transistor behavior. When two identical ambipolar transistors were integrated to establish an inverter structure, a voltage gain of 10 was obtained. The results indicate that these heterostructures can be utilized for the complementary circuits. (C) 2008 American Institute of Physics.
Annealing effect of polymer bulk heterojunction solar cells based on polyfluorene and fullerene blend
(2009-02-01)
Huang, Jen-Hsien
;
Yang, Chuan-Yi
;
Ho, Zhong-Yo
;
Kekuda, Dhananjay
;
Wu, Meng-Chyi
Control of blend morphology at the nanoscale and high charge mobility is essential for polymer photovoltaic devices in terms of their power conversion efficiencies (PCE). In the case of bulk heterojunctions solar cells, both blend morphology and charge mobility are influenced by thermal treatment. In this manuscript, we study the effects of annealing temperature on polymer PV devices with blends of poly[9,9'-dioctyl-fluorene-co-bithiophene] (F8T2) and [6,6]-phenyl-C(61)-butyric acid methyl ester (PCBM). The morphological changes of blended films were observed upon thermal annealing temperature near and above glass transition temperature (130 degrees C). Such microstructural transformations resulted in modified charge transport pathways and therefore greately influenced the device performance. The highest PCE of 2.14% with an open-circuit voltage (V(OC)) of 0.99 V and a short-circuit current (J(SC)) of 4.24 mA/cm(2) was achieved by device annealing at 70 degrees C for 20 min. (C) 2008 Elsevier B.V. All rights reserved.
Balancing the ambipolar conduction for pentacene thin film transistors through bifunctional electrodes
(2008-06-23)
Yang, Chuan-Yi
;
Dhananjay
;
Cheng, Shiau-Shin
;
Ou, Chun-Wei
;
Chuang, You-Che
We report an effective way to equilibrate hole and electron transport in ambipolar pentacene thin film transistors (TFTs). It was achieved by inserting an ultra thin lithium fluoride (LiF) layer at the electrode/organic interface to form a bifunctional source/drain electrode. It can be observed that the presence of ultrathin LiF layer will facilitate the injection of electrons from source/drain electrodes to organic semiconductor, resulting in a significant enhancement of the n-channel conduction, without sacrificing p-channel conduction for ambipolar pentacene TFTs. These factors make them potential candidates for the organic complementary circuits and inverter circuits of these ambipolar TFTs are also demonstrated. (c) 2008 American Institute of Physics.
Dependence of channel thickness on the performance of In(2)O(3) thin film transistors
(2008-05-07)
Dhananjay
;
Cheng, Shiau-Shin
;
Yang, Chuan-Yi
;
Ou, Chun-Wei
;
Chuang, You-Che
Bottom gate and top contact thin film transistors were fabricated using In(2)O(3) thin films as active channel layers. Thin films of varying thicknesses in the range 5 - 20 nm were deposited on an SiO(2) gate dielectric by the thermal evaporation process in the presence of high purity oxygen. The results of atomic force microscopy show that all the films exhibit dense grain distribution with a root-mean-square roughness in the range 0.6-8.0 nm. Irrespective of the thickness of the channel layer, the on/off ratio of the device is 10(4). The channel mobility and resistivity were found to be a strong function of the thickness of the active layer. The Levinson model was used to calculate the trap density and the grain boundary mobility. The low processing temperature shows the possibility of utilizing these devices on flexible substrates such as polymer substrates.
Dependence of channel thickness on the performance of In2O3 thin film transistors
(2008-05-07)
Dhananjay
;
Cheng, Shiau-Shin
;
Yang, Chuan-Yi
;
Ou, Chun-Wei
;
Chuang, You-Che
Bottom gate and top contact thin film transistors were fabricated using In2O3 thin films as active channel layers. Thin films of varying thicknesses in the range 5 - 20 nm were deposited on an SiO2 gate dielectric by the thermal evaporation process in the presence of high purity oxygen. The results of atomic force microscopy show that all the films exhibit dense grain distribution with a root-mean-square roughness in the range 0.6-8.0 nm. Irrespective of the thickness of the channel layer, the on/off ratio of the device is 10(4). The channel mobility and resistivity were found to be a strong function of the thickness of the active layer. The Levinson model was used to calculate the trap density and the grain boundary mobility. The low processing temperature shows the possibility of utilizing these devices on flexible substrates such as polymer substrates.
Determinants of the valuation of intangible assets - a contrast between Taiwanese and American IC design houses
(2008)
Chu, Po-Young
;
Hsiung, Hsing-Hwa
;
Huang, Chi-Hung
;
Yang, Chuan-Yi
;
管理科學系
The industry of IC design is asset-light but knowledge intensive and high value added. We undertook research to understand how US and Taiwan IC design houses evaluate their intangible assets, and what factors drive the value. The results show that the values of US IC design houses are higher than those of Taiwan by market capital methods. By contrast, the values of Taiwanese IC design houses are more consistent those of US firms using asset return methods. We then constructed 26 items from financial and intellectual capital aspects, and ran a factor analysis that returned eight main attributes of intangible value. Results of stepwise regression indicated that current profitability is the most important predictor of intangible value for Taiwan companies, whereas R&D productivity is the most important driver for US firms. These findings suggest that US design houses are more long-term focused in their operations than their Taiwanese counterparts.
Influence of thin metal base thickness on the performance of CuPc vertical organic triodes
(2007-04-09)
Cheng, Shiau-Shin
;
Yang, Chuan-Yi
;
Chuang, You-Che
;
Ou, Chun-Wei
;
Wu, Meng-Chyi
In this letter, the characteristics of vertical organic triodes fabricated by using two copper phthalocyanine (CuPc) back-to-back Schottky diodes with different metal base thicknesses are reported. The vertical organic triodes exhibit pronounced saturation regions in the output current-voltage characteristics. The common-emitter current gain reduces with increasing the Al base thickness due to the increase of recombination current at the base end resulted from the reduction of opening voids in the Al metal film. The common-emitter current gain of the device with 4.5 nm thick Al base reaches 1.9 at V-CE=-6 V and J(B)=2.5 mA/cm(2). (c) 2007 American Institute of Physics.
Pentacene thin-film transistor with PVP-capped high-k MgO dielectric grown by reactive evaporation
(2008)
Cheng, Shiau-Shin
;
Yang, Chuan-Yi
;
Ou, Chun-Wei
;
Chuang, You-Che
;
Wu, Meng-Chyi
Pentacene thin-film transistors operated at low voltages have been realized by employing hybrid dielectrics, poly(4-vinylphenol) (PVP)-capped MgO. The MgO film was deposited by reactive evaporation of magnesium in oxygen. The PVP layer plays a role in modifying the surface morphology of the MgO layer, and the images of atomic force microscopy for the PVP-capped MgO films show a root-mean-square roughness of 1 nm. The hybrid dielectric has a dielectric constant of 7.05 with a dielectric strength. The fabricated pentacene organic thin-film transistors exhibit a mobility of 0.66 cm(2)/V s, a threshold voltage of -2.67 V, and an on/off ratio of 10(3). (c) 2008 The Electrochemical Society.
Realization of ambipolar pentacene thin film transistors through dual interfacial engineering
(2008-05-01)
Yang, Chuan-Yi
;
Cheng, Shiau-Shin
;
Ou, Chun-Wei
;
Chuang, You-Che
;
Wu, Meng-Chyi
Ambipolar conduction of a pentacene-based field-effect transistor can be attributed to dual interface engineering, which occurs at the dielectric/semiconductor interface and electrode/semiconductor interface. While the former was realized by utilizing a hydroxyl-free gate dielectric, the latter was made feasible by the use of appropriate metal source and drain electrodes. The field-effect hole and electron mobilities of 0.026 and 0.0023 cm(2)/V s, respectively, were extracted from the transfer characteristics of pentacene organic field-effect transistors utilizing polymethyl methacrylate as the trap-reduction interfacial modified layer and Al as the source and drain (S/D) electrodes. We demonstrated a complementarylike inverter by using two identical ambipolar transistors and it can be operated both in the first and third quadrants with a high output voltage gain of around 10. (C) 2008 American Institute of Physics.
Solvent-Annealing-Induced Self-Organization of Poly(3-hexylthiophene), a High-Performance Electrochromic Material
(2009-12-01)
Huang, Jen-Hsien
;
Yang, Chuan-Yi
;
Hsu, Chih-Yu
;
Chen, Cheng-Lun
;
Lin, Lu-Yin
We have systematically studied the self-organization of poly(3-hexylthiophene) (P3HT), an electrochromic material, upon control of the solvent evaporation race. We characterized these polymer films using atomic force microscopy and X-ray diffraction measurements. Well-ordered P3HT structures were developed after solvent annealing; these highly crystalline structures exhibited enhanced electrochromic contrast and reduced resistance within the film, leading to larger coloration efficiencies and faster switching times. The optical contrast (Delta%T), coloration efficiency, and switching time of the P3HT films increased from 54.2%, 182,6 cm(2) C(-1), and 5.3 s, respectively, prior to solvent annealing to 64.8%, 293.5 cm(2) C(-1), and 3.2 s, respectively, after application of the solvent-annealing conditions.