Browsing by Author "Sheu, Jeng-Tzong"

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AC electrokinetics assisted impedance biosensors for rapid bacteria detection
(2012)
Ho, Yi-Tse
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Pan, Chun-Liang
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Sheu, Jeng-Tzong
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Wang, Yu-Kuo
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Wu, Tung-Kung
Early detection of living bacteria attracts a lot of attention in infection diseases applications, especially at low concentration. Nowadays, the detection of specific bacteria faces challenges including enhancement of trapping efficiency, and increase of sensor sensitivity and specificity. In this study, we improved the trapping efficiency and increased sensor sensitivity and specificity by using AC electrokinetics and selective modification of antibody on gold electrode in a new structure of gold electrode design. COMSOL simulations of AC electrokinetics include dielectrophoresis (DEP), and AC electroosmosis (ACEO) were performed on different electrode designs and bias configurations. The simulation results were consistent with the fluorescence observations showing that the bacteria were trapping selectively on gold electrodes. The impedance measurements for Vibrio parahaemolyticus (Vp) detection at 10(5) cfu/ml with AC elctrokinetics showed a nearly 90% change in normalized impedance change (NIC).
An optical programming/electrical erasing memory device: Organic thin film transistors incorporating core/shell CdSe@ZnSe quantum dots and poly(3-hexylthiophene)
(2009-08-01)
Chiu, Mao-Yuan
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Chen, Chen-Chia
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Sheu, Jeng-Tzong
;
Wei, Kung-Hwa
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材料科學與工程學系
An optical programming/electrical erasing memory device was fabricated by adopting organic thin film transistors incorporating core/shell CdSe@ZnSe quantum dots (QDs) and poly(3-hexylthiophene) (P3HT) as active layers. After illumination, the presence of quantum well-structured core/shell CdSe@ZnSe QDs within the P3HT film enhanced the maximum ON/OFF ratio substantially to 2700; this value was maintained for 8000 s without noticeable decay. The ON state current could be erased effectively when using a single pulse of the gate voltage (- 10 V). This fabrication approach opens up the possibility of improving the memory performance of polymeric materials prepared at low cost using simple processes, (C) 2009 Elsevier B.V. All rights reserved.
Characteristics of Gate-All-Around Junctionless Polysilicon Nanowire Transistors With Twin 20-nm Gates
(2015-09-01)
Liu, Tung-Yu
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Pan, Fu-Ming
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Sheu, Jeng-Tzong
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材料科學與工程學系奈米科技碩博班
;
分子醫學與生物工程研究所
A high performance gate-all-around (GAA) junctionless (JL) polycrystalline silicon nanowire (poly-Si NW) transistor with channel width of 12 nm, channel thickness of 45 nm, and gate length of 20 nm has been successfully demonstrated, based on a simplified double sidewall spacer process. Without suffering serious short-channel effects, the GAA JL poly-Si NW device exhibits excellent electrical characteristics, including a subthreshold swing of 105 mV/dec, a drain-induced barrier lowering of 83 mV/V, and a high I-on/I-off current ratio of 7 x 10(8) (V-G = 4 V and V-D = 1 V). Such GAA JL poly-Si NW devices exhibit potential for low-power electronics and future 3-D IC applications.
Characteristics of Gate-All-Around Twin Poly-Si Nanowire Thin-Film Transistors
(2009-02-01)
Sheu, Jeng-Tzong
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Huang, Po-Chun
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Sheu, Tzu-Shiun
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Chen, Chen-Chia
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Chen, Lu-An
We have investigated the characteristics of gate-all-around (GAA) twin polycrystalline-silicon nanowire (NW) thin-film transistors (TFTs). The NW channel and surrounding gate imparted the GAA twin NW TFT with superior channel controllability. Moreover, the combination of the high surface-to-volume ratio of the NW and the split channel structure led to highly efficient NH(3) plasma treatment, which reduced the effective grain-boundary trap-state density. The GAA twin NW TFT exhibited greatly improved electrical performance, including a lower threshold voltage, a steeper subthreshold swing (114 mV/dec), a higher on/off current ratio (> 10(8)), and a virtual absence of drain-induced barrier lowering (1.3 mV/V).
Controlled functionalization of a double-junction n(+)/n(-)/n(+) polysilicon nanobelt for hydrogen sensing application
(2016-04-01)
Nhan Ai Tran
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Sang, Chen-Hsiang
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Pan, Fu-Ming
;
Sheu, Jeng-Tzong
;
材料科學與工程學系奈米科技碩博班
In this paper, a double-junction n(+)/n(-)/n(+) polysilicon nanobelt selectively functionalized with platinum has been studied for hydrogen sensing application. The selective modification of the devices is performed by the combination of localized ablation of a resist and a lift-off process of e-beam evaporation of a catalyst material. The coverage of a Pt layer on the n(-) region is precisely controlled by adjusting Joule heating bias and pulse length. The Pt-functionalized devices show a rapid response to hydrogen with a limit of detection of only 5 ppm. The device with fully Pt-covered n(-) region is optimum for obtaining the best response to hydrogen. (C) 2016 The Japan Society of Applied Physics
Controlled functionalization of a double-junction n(+)/n(-)/n(+) polysilicon nanobelt for hydrogen sensing application
(2016-04)
Nhan Ai Tran
;
Sang, Chen-Hsiang
;
Pan, Fu-Ming
;
Sheu, Jeng-Tzong
;
材料科學與工程學系
In this paper, a double-junction n(+)/n(-)/n(+) polysilicon nanobelt selectively functionalized with platinum has been studied for hydrogen sensing application. The selective modification of the devices is performed by the combination of localized ablation of a resist and a lift-off process of e-beam evaporation of a catalyst material. The coverage of a Pt layer on the n(-) region is precisely controlled by adjusting Joule heating bias and pulse length. The Pt-functionalized devices show a rapid response to hydrogen with a limit of detection of only 5 ppm. The device with fully Pt-covered n(-) region is optimum for obtaining the best response to hydrogen. (C) 2016 The Japan Society of Applied Physics
Effectiveness of organic molecules for spin filtering in an organic spin valve: Reaction-induced spin polarization for Co atop Alq(3)
(2015-01-21)
Tu-Ngoc Lam
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Lai, Yu-Ling
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Chen, Chih-Han
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Chen, Po-Hung
;
Chan, Yuet-Loy
The spin polarization of organic-ferromagnetic interfaces in an organic spin valve critically affects the efficiency of spin injection or detection. We examined the chemical and electronic properties of ferromagnetic Co deposited on organic Alq(3) and the interfacial spin-polarized capability of the electronic states. Our x-ray photoemission spectra and calculations with density-functional theory indicate a sequential and unequal distribution of charge from Co clusters to N and then to O atoms in Alq(3). The preferential orbital hybridization at specific functional sites produces efficient spin polarization of organic molecules. Element-specific measurements of x-ray magnetic circular dichroism demonstrate the preferential spin polarization in the lowest unoccupied molecular orbital state of N atoms at the complex interface for Co atop Alq(3), which agrees satisfactorily with calculation. Our results indicate that an induced interfacial spin polarization on engineering the dominant reaction of Co with mainly N and O atoms in Alq(3) might pave a way for effective spin filtering in organic spintronics.
Electric-Field Enhancement of a Gate-All-Around Nanowire Thin-Film Transistor Memory
(2010-03-01)
Huang, Po-Chun
;
Chen, Lu-An
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Sheu, Jeng-Tzong
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材料科學與工程學系
;
材料科學與工程學系奈米科技碩博班
A high-performance gate-all-around (GAA) poly-Si nanowire (NW) SONOS-type memory thin-film transistor (TFT) is presented. The presence of the corners of the GAA structure resulted in the program speed and memory window of this device being superior to those of a planar poly-Si TFT device. When erasing, planar devices exhibit a threshold-voltage shift resulting from gate injection; the GAA device was immune to this behavior. The presence of a nonuniform electric field in the channel region during programming and erasing was confirmed through simulation. The device also exhibited superior endurance and data-retention behavior.
Electrical bistable memory device based on a poly(styrene-b-4-vinylpyridine) nanostructured diblock copolymer thin film
(2008-11-17)
Huang, Ching-Mao
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Liu, Yung-Sheng
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Chen, Chen-Chia
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Wei, Kung-Hwa
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Sheu, Jeng-Tzong
This paper describes the performance of a nonvolatile memory device based on a solution-processed poly(styrene-b-4-vinylpyridine) (PS-b-P4VP) diblock copolymer thin film. The Al/PS-b-P4VP/indium tin oxide memory device featuring metal-coordinated 30 nm P4VP cores exhibited an ON/OFF ratio of 2x10(5), an erase voltage of 0.75 V, a write voltage of -0.5 V, and a retention time of 10(4) s. The device exhibited a metallic behavior in the ON state, suggesting the formation of metallic filaments through the migration of Al atoms into the P4VP domain during writing. Such nanostructured diblock copolymer thin films open up avenues for fabricating organic memory devices using simple procedures.
Enhancement of detection by selective modification of silicon nanobelt field-effect transistors via localized Joule heating
(2014-03-01)
Liu, Hao Heng
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Lin, Tzung Han
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Sheu, Jeng-Tzong
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材料科學與工程學系奈米科技碩博班
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Graduate Program of Nanotechnology , Department of Materials Science and Engineering
We utilized localized Joule heating to ablate methoxy-poly (ethylene-glycol)-silane (mPEG-sil) modified on the p(-) region of an n(+)-p(-)-n(+) silicon nanobelt field-effect transistor (SNFET). SNFETs with selective modifications of 3-aminopropyltrimethoxysilane (APTMS) and NHS-biotin on the ablated region exhibited a faster sensing response rate and a higher sensitivity in real-time detection of Streptavidin (SA). Characterization of the ablated region via lateral force microscopy and the fluorescence image show that the ablation region occurs only in the p(-) region near the drain side and is believed to be a result of the impact ionization mechanism during Joule heating. Moreover, a bias of 20 V pulse voltage for 1 ms successfully ablates mPEG-sil and reduces the device off leakage current by 1 order after Joule heating. However, Joule heating with a pulse voltage larger than 20V (1 ms) yielded an increase of device off leakage owing to damage to gate dielectrics during Joule heating. A comparison of real-time detection of SA between selectively and non-selectively modified chips shows that selectively modified ones exhibit a better limit of detection (LOD) that is one order lower than non-selectively modified ones, and a sensing response rate twice as fast as the non-selectively modified one for every target concentration. (C) 2013 Elsevier B.V. All rights reserved.
Fluorescence enhancement and multiple protein detection in ZnO nanostructure microfluidic devices
(2016-01-15)
Sang, Chen-Hsiang
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Chou, Shu-Jen
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Pan, F. M.
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Sheu, Jeng-Tzong
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材料科學與工程學系
In this study, different morphological ZnO nanostructures, those of sharp nanowires (NWs), rod NWs, and hexahedral-puncheon nanostructures, were grown in microfluidic channels on the same glass substrate. Characterizations of correspondent biomolecule binding properties were simulated and demonstrated. The surface was modified using 3-ammineopropyl-triethoxysilane (3-APTES) and biotin-N-hydroxysuccinimide ester (NHS-biotin). Different concentrations (4.17 pM to 41.7 nM) of dye-conjugated streptavidin were simultaneously infused through the second microfluidic channels, which lie 90 degrees from the first microfluidic channels. The florescent intensity at the crossover areas showed good agreement with simulations, with sharp ZnO NWs exhibiting the largest dynamic range and the highest fluorescent intensity. We further characterize correspondent protein detection using sharp ZnO NWs. The surfaces of these ZnO NWs were modified with mouse immunoglobulin G (IgG), infused through the second microfluidic channels with dye-conjugated (Alexa 546) anti-mouse IgG in different concentrations. Concentrations ranging from 417 fM to 41.7 nM can be resolved using sharp ZnO NWs. Finally, multiple protein detection was demonstrated using a five-by-eight microfluidic channel array. Fluorescence images present clear multiple detections at the crossover areas when using the sharp ZnO NWs for simultaneous dye-conjugated anti-mouse IgG and dye-conjugated anti-rabbit IgG (Alexa 647) detection. (C) 2015 Elsevier B.V. All rights reserved.
Gate-all-around poly-Si nanowire junctionless thin-film transistors with multiple channels
(2015-06-01)
Tso, Chia-Tsung
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Liu, Tung-Yu
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Sheu, Jeng-Tzong
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材料科學與工程學系
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Department of Materials Science and Engineering
Polycrystalline silicon (poly-Si) nanowire (NW) junctionless (JL) thin-film transistors composed of gate-all-around (GAA) and multiple channels were demonstrated and characterized. The high surface-to-volume ratio of the NW and a nominal gate length of 0.25 mu m lead to a clear improvement in electrical performance, including a steep subthreshold swing (SS; similar to 124 mV/decade), a virtual absence of drain-induced barrier lowering (DIBL; 21 +/- 13 mV/V), and a high I-ON/I-OFF current ratio (similar to 1 x 10(9)) under a relatively low voltage condition (V-D = 0.3 V, V-G = 5 V), resulting from the multiple-channel structure and small grain boundaries and defects under the gate area. (C) 2015 The Japan Society of Applied Physics
Gate-All-Around Single-Crystal-Like Poly-Si Nanowire TFTs With a Steep-Subthreshold Slope
(2013-04-01)
Liu, Tung-Yu
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Lo, Shen-Chuan
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Sheu, Jeng-Tzong
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材料科學與工程學系
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Department of Materials Science and Engineering
We investigate the characteristics of single-crystallike (SCL) poly-Si nanowire (SCL poly-Si NW) thin-film-transistors with gate-all-around (GAA) structures. The GAA SCL poly-Si NWs are prepared by a modified sidewall spacer process utilizing an amorphous silicon (alpha-Si) mesa structure. The combination of the high surface-to-volume ratio of the NW and a nominal gate length of 0.25 mu m lead to clear improvement in electrical performance, including a steep subthreshold swing (90 +/- 15 mV/dec), a virtual absence of drain-induced barrier lowering (21 +/- 13 mV/V), and a very high ON/OFF current ratio similar to 7 x 10(7) (V-D = 1 V, V-G = 3 V).
Gray-level patterning of gold nanoparticles with scanning probe lithography of self-assembly monolayer
(2007)
Sheu, Jeng-Tzong
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Wu, Chia-Hao
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Liu, Hao-Heng
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Chao, Tieng-Sheng
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材料科學與工程學系奈米科技碩博班
Growth and Field Emission of Reactive Sputtered Pd-PdO Core-Shell Nanoflakes on Platinum
(2009)
Huang, Chien-Jung
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Pan, Fu-Ming
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Tzeng, Tai-Cheng
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Li-Chang
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Sheu, Jeng-Tzong
Palladium oxide (PdO) was deposited on platinum by reactive sputter deposition, and the PdO thin film grown on the Pt substrate had a flakelike morphology. The nanosized flake had a core-shell structure with a single Pd grain encapsulated by a crystalline PdO surface layer. The formation of the PdO capped nanoflakes was ascribed to a large interfacial stress due to a lattice mismatch between PdO and Pt. Field emission characteristics of the nanoflakes were studied and a field-enhancement factor of 791 was obtained.
Hydrogen gas sensors from polysilicon nanobelt devices selectively modified with sensing materials
(2016-12-16)
Nhan Ai Tran
;
Pan, Fu-Ming
;
Sheu, Jeng-Tzong
;
材料科學與工程學系
;
分子醫學與生物工程研究所
Double-junction n(+)/n(-)/n(+) polysilicon nanobelts featuring selectively deposited sensing materials have been investigated for application as H-2 gas sensors. The selective modification of the devices was performed through a combination of localized ablation of a resist and lift-off of a previous catalyst material deposited through e-beam evaporation. Four nanobelt devices, differentiated by their doping concentrations at the n(-) region (from 2.5. x. 10(13) to 2.5. x. 10(14) cm(-2)), were analyzed in terms of the responses to H-2 and their self-heating effects. A low doping concentration improved the response at room temperature, owing to a longer Debye length. The variation in the H-2-induced surface potential associated with temperature, accounting for degradation in the response of the nanobelts with Joule heating bias, was analyzed in terms of the I-V characteristics of the double-junction device. Among various catalysts (Pt, Pd, Pt/Pd) evaluated for their H-2 sensing characteristics, an ultrathin film of Pt/Pd was most favorable.
Intensify the application of ZnO-based nanodevices in humid environment: O-2/H-2 plasma suppressed the spontaneous reaction of amorphous ZnO nanowires
(2014-06-02)
Lai, Chun-Yen
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Chien, Tzu-Chiao
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Lin, Ting-Yi
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Ke, Teng
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Hsu, Shih-Han
In this work, we have demonstrated that amorphous ZnO nanobranches (a-ZnO NBs) could spontaneously react from the crystalline ZnO NWs (c-ZnO NWs) at specific humid environment. The spontaneous reaction mechanism and result can be analyzed by humidity controlling and optical microscope (OM)/scanning electron microscope (SEM)/Kelvin probe force microscopy (KPFM)/transmission electron microscopy (TEM) system. We can make the c-ZnO NWs spontaneous reaction happen at different humid environments and suppress the a-ZnO NBs spontaneous reaction by oxygen/hydrogen plasma surface passivation. The hydrogen plasma surface treatment also can improve the UV sensing sensitivity more than twofold. This work provides the mechanism and methods of the a-ZnO NBs spontaneous growth and offers the passivation treatment for strengthening and enhancing ZnO-based nanodevice application in humid environment and UV light detection, respectively.
Interfacial symmetry of Co-Alq(3)-Co hybrid structures for effective spin filtering
(2015-11-01)
Lam, Tu-Ngoc
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Lai, Yu-Ling
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Chen, Chih-Han
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Chen, Po-Hung
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Wei, Der-Hsin
Understanding the interfacial behavior at FM-OSC-FM hybrid structures for both the bottom contact (Alq(3) adsorption on Co, Co/Alq(3)) and the top contact (Co atop Alq(3), Alq(3)/Co) is crucial for efficient spin filtering with transport of spin-polarized charge carriers through these interfaces. X-ray photoelectron spectroscopy (XPS) spectra indicate a symmetry of charge transfer from Co to Alq(3) and the corresponding orbital hybridization to a certain extent at both contacts. The alignment of energy levels at both Alq(3)/Co and Co/Alq(3) heterostructures is depicted with ultraviolet photoelectron spectroscopy (UPS). Through magnetic images acquired with a X-ray photoemission electron microscope (XPEEM), the strong hybridization of the top contact presents no micromagnetic domain but still shows magnetic coupling, to some extent, to the bottom contact in the Co-Alq(3)-Co trilayer structure. Measurements of X-ray magnetic circular dichroism (XMCD) demonstrate the induced spin-polarization of non-magnetic Alq(3) at both contacts, proving Alq(3) a unique and promising organic material for spin filtering in OSV. (C) 2015 Elsevier B.V. All rights reserved.
Interfacial symmetry of Co-Alq(3)-Co hybrid structures for effective spin filtering (vol 354, pg 90, 2015)
(2018-05-31)
Tu-Ngoc Lam
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Lai, Yu-Ling
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Chen, Chih-Han
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Chen, Po-Hung
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Wei, Der-Hsin
Junctionless gate-all-around nanowire field-effect transistors with an extended gate in biomolecule detection
(2019-02-01)
Chen, Chih-Wei
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Lin, Ru-Zheng
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Chiang, Li-Chuan
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Pan, Fu-Ming
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Sheu, Jeng-Tzong
In this study, we investigated the potential drift and sensitivity in an extended-gate (EG) field-effect-transistor (FET)-based potentiometric sensor with junctionless (JL) and inversion-mode (IM) gate-all-around (GAA) nanowire (NW) FETs. An EG electrode (EGE) coated with Al2O3 via plasmaenhanced atomic-layer deposition exhibited high stability. Both JL and IM GAA NWFETs were prepared in the same batch and exhibited high electrical performance, including a steep subthreshold swing of approximately 63 mV dec(-1) and a high ON/OFF current ratio of approximately 3 x 10(7) at V-DS = 0.1 V. However, JL GAA NWFETs exhibited higher drift stability than did IM GAA NWFETs under various working regions over a long period of operation. Furthermore, JL GAA NWFETs with EGEs (JL GAA NWFETs w-EGEs) exhibited the highest sensitivity when operating under the subthreshold region in pH sensing (Delta I/I-0 = similar to 4410%). The readout sensitivity reached S-out = 82%. A JL GAA NWFET w-EGE was also demonstrated as a potentiometric biosensor for streptavidin real-time detection at concentrations of 42 fM to 4.2 nM. (C) 2019 The Japan Society of Applied Physics