Browsing by Author "Cheng, Shiau-Shin"

Now showing 1 - 14 of 14

A cascade energy band structure enhances the carrier energy in organic vertical-type triodes
(2013-09-01)
Cheng, Shiau-Shin
;
Ramesh, Mohan
;
Chen, Guan-Yuan
;
Fung, Chun-Lin
;
Chen, Li-Ming
Organic vertical-type triodes (OVTs) based on the cascade energy band structure as emitter layer are studied. The electric characteristics were dramatically enhanced while incorporating the cascade energy under current driving and voltage driving modes. The improvement is attributed to that injection carriers can obtain higher energy through a stepwise energy level. When the device has a layered structure of F16CuPC (10 nm)/PTCDI (10 nm)/pentacene (100 nm) in emitter, it exhibits a common-base transport factor of 0.99 and a common-emitter current gain of 225 under current driving mode and exhibits a high current modulation-exceeding -520 mu A for a low collector voltage of -5 V and a base voltage of -5 V and the current on/off ratio of 10(3) under voltage driving mode. Furthermore, we realized first organic current mirror that exhibited out/in current ratio of 0.75 and output resistance of 10(5) Omega by using the OVTs. (C) 2013 Published by Elsevier B.V.
Anomalous p-channel amorphous oxide transistors based on tin oxide and their complementary circuits
(2008-03-24)
Ou, Chun-Wei
;
Ho, Zhong Yo
;
Chuang, You-Che
;
Cheng, Shiau-Shin
;
Wu, Meng-Chyi
In this article, we report the fabrication of SnO(2) thin film transistors (TFTs) fabricated by reactive evaporation. Different from the previous reports, the fabricated TFTs exhibit p-type conductivity in its undoped form. The postdeposition annealing temperature was tuned to achieve p-channel SnO(2) TFTs. The on/ off ratio and the field-effect mobility were similar to 10(3) and 0.011 cm(2)/V s, respectively. To demonstrate inverter circuit, two devices with different threshold voltages were combined and an output gain of 2.8 was achieved. The realization of p-channel oxide TFTs would open up new challenges in the area of transparent electronics. (C) 2008 American Institute of Physics.
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.
Hybrid TiO(x)/fluoropolymer bi-layer dielectrics for low-voltage complementary inverters
(2010-01-01)
Sung, Chao-Feng
;
Kekuda, Dhananjay
;
Chu, Li Fen
;
Chen, Fang-Chung
;
Cheng, Shiau-Shin
In this article, low temperature processed, reactively evaporated titanium oxide layers were utilized as gate dielectrics for achieving low voltage driven transistors and complementary inverters. The surface of the gate dielectric was modified by an ultra thin (similar to 30 nm) fluoropolymer Cytop (R) layer which partially helped to reduce the leakage in the dielectric films and also enhanced the organic transistor performance. The current investigation demonstrates the ability of these high capacitance bi-layer dielectrics (k similar to 20). The combined p-type and n-type field-effect transistors show similar saturation mobility similar to 0.3 cm(2)/Vs to achieve low voltage driven complementary circuits with output gain of 22. Low temperature processing of these dielectric layers make them easily integrated. (C) 2009 Elsevier B.V. All rights reserved.
Hybrid TiOx/fluoropolymer bi-layer dielectrics for low-voltage complementary inverters
(2010-01-01)
Sung, Chao-Feng
;
Kekuda, Dhananjay
;
Chu, Li Fen
;
Chen, Fang-Chung
;
Cheng, Shiau-Shin
In this article, low temperature processed, reactively evaporated titanium oxide layers were utilized as gate dielectrics for achieving low voltage driven transistors and complementary inverters. The surface of the gate dielectric was modified by an ultra thin (similar to 30 nm) fluoropolymer Cytop (R) layer which partially helped to reduce the leakage in the dielectric films and also enhanced the organic transistor performance. The current investigation demonstrates the ability of these high capacitance bi-layer dielectrics (k similar to 20). The combined p-type and n-type field-effect transistors show similar saturation mobility similar to 0.3 cm(2)/Vs to achieve low voltage driven complementary circuits with output gain of 22. Low temperature processing of these dielectric layers make them easily integrated. (C) 2009 Elsevier B.V. All rights reserved.
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.
Low-voltage complementary inverters employing organic vertical-type triodes
(2010-04-01)
Cheng, Shiau-Shin
;
Chen, Guan-Yuan
;
Chen, Jia-Hao
;
Wu, Meng-Chyi
;
Chu, Chih-Wei
In this study, we report the electrical characterization of complementary inverters fabricated using n- and p-channel organic vertical-type triodes (OVTs) on the same substrate. Because of the similar performance of the p-channel OVT (ON current: similar to 229 mu A; OFF current: similar to 67.6 nA; turn-on voltage: similar to 0.8 V) and n-channel OVT (ON current: 377 mu A; OFF current: 86.9 nA; turn-on voltage: 0.4 V), the complementary inverter combining the n- and p-channel OVTs exhibited a voltage gain of ca. 9 at a low supply voltage of 4 V. (C) 2009 Elsevier B. V. All rights reserved.
Organic Base Modulation Triodes and Their Inverters on Flexible Substrates
(2009-05-11)
Cheng, Shiau-Shin
;
Chuang, You-Che
;
Kekuda, Dhananjay
;
Ou, Chun-Wei
;
Wu, Meng-Chyi
Organic base modulation triodes (OBMTs) are fabricated using two back-to-back Schottky diodes and deposited on a flexible substrate. With the advantage of the shorter channel, the OBMTs can be operated under lower voltages and faster frequencies. The inverter is fabricated using the OBMT connected with a resistor in series.
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.
Solution-Processed Small-Molecule Bulk Heterojunction Ambipolar Transistors
(2014-04-01)
Cheng, Shiau-Shin
;
Huang, Peng-Yi
;
Ramesh, Mohan
;
Chang, Hsiu-Chieh
;
Chen, Li-Ming
Solution-processed small-molecule bulk heterojunction (BHJ) ambipolar organic thin-film transistors are fabricated based on a combination of [2-phenylbenzo[d,d \']thieno[3,2-b;4,5-b \']dithiophene (P-BTDT) : 2-(4-n-octylphenyl)benzo[d,(d) under bar \']thieno[3,2-b;4,5-b\']dithiophene (OP-BTDT)] and C-60. Treating high electrical performance vacuum-deposited P-BTDT organic semiconductors with a newly developed solution-processed organic semiconductor material, OP-BTDT, in an optimized ratio yields a solution-processed p-channel organic semiconductor blend with carrier mobility as high as 0.65 cm(2) V-1 s(-1). An optimized blending of P-BTDT:OP-BTDT with the n-channel semiconductor, C-60, results in a BHJ ambipolar transistor with balanced carrier mobilities for holes and electrons of 0.03 and 0.02 cm(2) V-1 s(-1), respectively. Furthermore, a complementary-like inverter composed of two ambipolar thin-film transistors is demonstrated, which achieves a gain of 115.
Using metal/organic junction engineering to prepare an efficient organic base-modulation triode and its inverter
(2009-12-01)
Cheng, Shiau-Shin
;
Chen, Jia-Hao
;
Chen, Guan-Yuan
;
Kekuda, Dhananjay
;
Wu, Meng-Chyi
In this study, we investigated the influence of a buffer layer of molybdic oxide (MoO(3)) at the metal/organic junction on the behavior of organic base-modulation triodes. The performance of devices featuring MoO(3)/Al as the emitter electrode was enhanced relative to that of corresponding devices with Au and Ag, presumably because of the reduced in the contact barrier and the prevention of metal diffusion into the organic layer. The device exhibited an output current of -16.1 mu A at V(B) = -5 V and a current ON/OFF ratio of 10(3). Using this architecture, we constructed resistance-load inverters that exhibited a calculated gain of 6. (C) 2009 Elsevier B.V. All rights reserved.