Browsing by Author "Chen, Yen-Ting"

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A 145 mu W 315MHz Harmonically Injection-Locked RF Transmitter with Two-Step Frequency Multiplication Techniques
(2017-01-01)
Dau, Nan
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Chen, Yen-Ting
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Liao, Yu-Te
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電機工程學系
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Department of Electrical and Computer Engineering
This paper presents a low-power RF transmitter with harmonic injection locking and capacitive-coupling frequency multiplication techniques. To save power, the design operates at a low frequency except for the RF Class-E power amplifier. The chip, which was fabricated using 0.18 um CMOS technology, has an area of 0.49 mm X 0.93 mm. The proposed model can achieve a maximum transmission power of -21.3 dBm, data rate of 2 Mbps, and energy efficiency of 0.071nJ/bit while consuming 145 mu W.
An Optically-Powered 432 MHz Wireless Tag for Batteryless Internet-of-Things Applications
(2019-09-01)
Cheng, Hao-Chung
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Chen, Yen-Ting
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Chen, Po-Hung
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Liao, Yu-Te
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電子工程學系及電子研究所
This paper presents an optically-powered wireless tag, integrating a charge pump (CP) and a low-power RF transmitter for batteryless Internet-of-Things (IoT) applications. The proposed charge pump with hysteresis regulation mechanism (HRM) powers the transmitter circuit using indoor light energy. The charge pump enables the transmitter whenever the output capacitor stores sufficient energy and guarantees a short period signal transmission. The proposed low-power transmitter contains the subharmonically injection-locked PLL and the capacitive coupling technique to achieve a large frequency multiplication ratio. The proposed batteryless wireless chip is fabricated in 0.18-mu m CMOS process. The measurement results demonstrate that the proposed charge pump provides a 1.1 to 1.3 V hysteresis regulated voltage under indoor light illumination larger than 300 lux. The charge pump achieves 84.1% peak efficiency and the communication distance of 3 meters is demonstrated while only consuming 248 mu W.
Beacon Jointed Packet Reconstruction Scheme for Mobile-Phone Based Visible Light Communications Using Rolling Shutter
(2017-12-01)
Wang, Wei-Chung
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Chow, Chi-Wai
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Chen, Chia-Wei
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Hsieh, Hsiang-Chain
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Chen, Yen-Ting
Mobile-phone based visible light communication (VLC) is an attractive method for optical wireless communication. However, the data rate is typically limited by the complementary metal-oxide-semiconductor image sensor frame rate and the processing time gap in the rolling shutter mode operation. Here, we propose and demonstrate a packet-reconstruction scheme, known as beacon jointed rolling shutter pattern scheme. The mobile-phone based VLC data rate can be increased to a record 10.32 kb/s. The implementation algorithm is discussed; and the bit-error-rate experimental evaluations at different transmission distances and horizontal offsets are performed.
Compact Bis-Adduct Fullerenes and Additive-Assisted Morphological Optimization for Efficient Organic Photovoltaics
(2014-11-26)
Lai, Yun-Yu
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Liao, Ming-Hung
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Chen, Yen-Ting
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Cao, Fong-Yi
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Hsu, Chain-Shu
Bis-adduct fullerenes surrounded by two insulating addends sterically attenuate intermolecular interaction and cause inferior electron transportation. In this research, we have designed and synthesized a new class of bis-adduct fullerene materials, methylphenylmethano-C-60 bis-adduct (MPC(60)BA), methylthienylmethano-C-60 bis-adduct (MTC(60)BA), methylphenylmethano-C-70 bis-adduct (MPC(70)BA), and methylthienylmethano-C-70 bis-adduct (MTC(70)BA), functionalized with two compact phenylmethylmethano and thienylmethylmethano addends via cyclopropyl linkages. These materials with much higher-lying lowest unoccupied molecular orbital (LUMO) energy levels successfully enhanced the V-oc values of the P3HT-based solar cell devices. The compact phenylmethylmethano and thienylmethylmethano addends to promote fullerene intermolecular interactions result in aggregation-induced phase separation as observed by the atomic force microscopy (AFM) and transmission electron microscopy (TEM) images of the poly(3-hexylthiophene-2,5-diyl) (P3HT)/bis-adduct fullerene thin films. The device based on the P3HT/MTC(60)BA blend yielded a V-oc of 0.72 V, a J(sc) of 5.87 mA/cm(2), and a fill factor (FF) of 65.3%, resulting in a power conversion efficiency (PCE) of 2.76%. The unfavorable morphologies can be optimized by introducing a solvent additive to fine-tune the intermolecular interactions. 1-Chloronaphthalene (CN) having better ability to dissolve the bis-adduct fullerenes can homogeneously disperse the fullerene materials into the P3HT matrix. Consequently, the aggregated fullerene domains can be alleviated to reach a favorable morphology. With the assistance of CN additive, the P3HT/MTC(60)BA-based device exhibited enhanced characteristics (a V-oc of 0.78 V, a J(sc) of 9.04 mA/cm(2), and an FF of 69.8%), yielding a much higher PCE of 4.92%. More importantly, the additive-assisted morphological optimization is consistently effective to all four compact bis-adduct fullerenes regardless of the methylphenylmethano or methylthienylmethano scaffolds as well as C-60 or C-70 core structures. Through the extrinsic additive treatment, these bis-adduct fullerene materials with compact architectures show promise for high-performance polymer solar cells.
DC and dynamic switching characteristics of field-plated vertical geometry beta-Ga2O3 rectifiers
(2019-01-01)
Yang, Jiancheng
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Carey, Patrick
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Ren, Fan
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Chen, Yen-Ting
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Liao, Y.
Reverse breakdown voltages larger than 1 kV have been reported for both unterminated Ga2O3 vertical rectifiers (1000-1600 V) and field-plated Schottky diodes (1076-2300 V) with an epi thickness of 8-20 mu m. If the doping is in the 10(16) cm range, the breakdown is usually in the 500-800V regime. Furthermore, the switching characteristics of discrete Ga2O3 vertical Schottky rectifiers exhibited reverse recovery times in the range of 20 to 30 ns. Large area (up to 0.2 cm(2)) Ga2O3 rectifiers were fabricated on a Si-doped n-Ga2O3 drift layer grown by halide vapor phase epitaxy on a Sn-doped n(+) Ga2O3 (001) substrate. A forward current of 2.2 A was achieved in single-sweep voltage mode, a record for Ga2O3 rectifiers. The on-state resistance was 0.26 Omega.cm(2) for these largest diodes, decreasing to 5.9 x 10 Omega.cm(2) for 40x40 mu m devices. We detail the design and fabrication of these devices. In addition, an inductive load test circuit was used to measure the switching performance of field-plated, edge-terminated Schottky rectifiers with a reverse breakdown voltage of 760 V (0.1 cm diameter, 7.85 x10(-3) cm(2) area) and an absolute forward current of 1 A on 8 mu m thick epitaxial beta-Ga2O3 drift layers. These devices were switched from 0.225 A to -700 V with t of 82 ns, and from 1 A to -300 V with t of 64 ns and no significant temperature dependence up to 125 degrees C. There was no significant temperature dependence of t(rr)up to 150 degrees C.
Dynamic Switching Characteristics of 1 A Forward Current beta-Ga2O3 Rectifiers
(2019-01-01)
Yang, Jiancheng
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Ren, Fan
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Chen, Yen-Ting
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Liao, Yu-Te
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Chang, Chin-Wei
An inductive load test circuit was used to measure the switching performance of field-plated edge-terminated Schottky rectifiers with a reverse breakdown voltage of 760 V (0.1 cm diameter, 7.85 x 10(-3) cm(2) area) and an absolute forward current of 1 A on 8 mu m thick epitaxial beta-Ga2O3 drift layers. The recovery characteristics for these vertical geometry beta-Ga2O3 Schottky rectifiers switching from forward current of 1 A to reverse off-state voltage of -300 V showed a recovery time (trr) of 64 ns. There was no significant temperature dependence of trr up to 150 degrees C.
Effect of thermal annealing for W/beta-Ga2O3 Schottky diodes up to 600 degrees C
(2019-11-01)
Xian, Minghan
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Fares, Chaker
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Ren, Fan
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Gila, Brent P.
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Chen, Yen-Ting
The electrical and structural properties of sputter-deposited W Schottky contacts with Au overlayers on n-type Ga2O3 are found to be basically stable up to 500 degrees C. The reverse leakage in diode structures increases markedly (factor of 2) for higher temperature annealing of 550-600 degrees C. The sputter deposition process introduces near-surface damage that reduces the Schottky barrier height in the as-deposited state (0.71 eV), but this increases to 0.81 eV after a 60 s anneal at 500 degrees C. This is significantly lower than conventional Ni/Au (1.07 eV), but W is much more thermally stable, as evidenced by Auger electron spectroscopy of the contact and interfacial region and the minimal change in contact morphology. The contacts are used to demonstrate 1.2 A switching of forward current to -300 V reverse bias with a reverse recovery time of 100 ns and a dI/dt value of 2.14 A/mu s. The on/off current ratios were >= 10(6) at -100V reverse bias, and the power figure-of-merit was 14.4 MW cm(-2). Published by the AVS.
Growth of sparse arrays of narrow GaN nanorods hosting spectrally stable InGaN quantum disks
(2012-07-16)
Chen, Yen-Ting
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Tsai, Wen-Che
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Chen, Wen-Yen
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Hsiao, Ching-Lien
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Hsu, Hsu-Cheng
Wafer-scale production of single InGaN quantum disks (QD) in-a-nanorod array with small rod diameter (> 9 nm) and low rod-density (< 10(8) cm(-2)) has been achieved without extensive processing steps. Excitation power-dependent mu PL spectrum of single QD reveals multi-excitonic peak with 0.75 meV blue-shift for 3 orders of magnitude increasing power, indicating the present system is spectrally stable and nearly free of quantum-confined Stark effects, due possibly to the strain relaxation induced by free surface of small rod diameters. The fully polarized emissions, a high working temperature (180 K), low rod density and good alignment, render this system promising as a potential quantum photon source. (C) 2012 Optical Society of America
Histone Demethylase RBP2 Promotes Lung Tumorigenesis and Cancer Metastasis
(2013-08-01)
Teng, Yu-Ching
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Lee, Cheng-Feng
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Li, Ying-Shiuan
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Chen, Yi-Ren
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Hsiao, Pei-Wen
The retinoblastoma binding protein RBP2 (KDM5A) is a histone demethylase that promotes gastric cancer cell growth and is enriched in drug-resistant lung cancer cells. In tumor-prone mice lacking the tumor suppressor gene RB or MEN1, genetic ablation of RBP2 can suppress tumor initiation, but the pathogenic breadth and mechanistic aspects of this effect relative to human tumors have not been defined. Here, we approached this question in the context of lung cancer. RBP2 was overexpressed in human lung cancer tissues where its depletion impaired cell proliferation, motility, migration, invasion, and metastasis. RBP2 oncogenicity relied on its demethylase and DNA-binding activities. RBP2 upregulated expression of cyclins D1 and E1 while suppressing the expression of cyclin-dependent kinase inhibitor p27 (CDKN1B), each contributing to RBP2-mediated cell proliferation. Expression microarray analyses revealed that RBP2 promoted expression of integrin-beta 1 (ITGB1), which is implicated in lung cancer metastasis. Mechanistic investigations established that RBP2 bound directly to the p27, cyclin D1, and ITGB1 promoters and that exogenous expression of cyclin D1, cyclin E1, or ITGB1 was sufficient to rescue proliferation or migration/invasion, respectively. Taken together, our results establish an oncogenic role for RBP2 in lung tumorigenesis and progression and uncover novel RBP2 targets mediating this role. (C)2013 AACR.
Implementation of a 900 V Switching Circuit for High Breakdown Voltage beta-Ga2O3 Schottky Diodes
(2019-05-22)
Chen, Yen-Ting
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Yang, Jiancheng
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Ren, Fan
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Chang, Chin-Wei
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Lin, Jenshan
This paper presents a switching circuit for high breakdown-voltage Ga2O3 vertical Schottky rectifiers. Field-plated edge-terminated (FPET) vertical Schottky diodes were fabricated on a 20-mu m thick Si-doped n-type Ga2O3 drift layer which was grown on the 650-mu m thick beta-Ga2O3 substrate via halide vapor phase epitaxy (HVPE). The measured reverse recovery time of the proposed Ga2O3 Schottky diode was 81 ns when switched to a reverse bias voltage of -900 V. The implementation of a switching circuit with the novel Ga2O3 diode is the first demonstrated at such a high switching voltage. This paper also provides insights for the practical implementation of the Ga2O3 vertical Schottky rectifiers from device fabrication to circuit design. (C) The Author(s) 2019. Published by ECS.
Reducing Regioisomers of Fullerene-Bisadducts by Tether-Directed Remote Functionalization: Investigation of Electronically and Sterically Isomeric Effects on Bulk-Heterojunction Solar Cells
(2014-01-22)
Liao, Ming-Hung
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Lai, Yin-Yu
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Lai, Yu-Ying
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Chen, Yen-Ting
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Tsai, Che-En
C-60 bis-adduct containing a mixture of regio-isomers with different LUMO energy levels and steric geometries could greatly affect the morphological and bulk properties. To investigate the regio-isomer effect on solar cell performance, we have successfully designed and synthesized a regio-selective 4-acetatephenyl-4'-methylphenylmethano C-60 bis-adduct (S-APM-CBA) by "tether-directed remote functionalization" strategy and a random 4-acetatephenyl-4'-methylphenylmethano C-60 bis-adduct denoted as R-APM-CBA by traditional cyclopropanation. The dramatic reduction in the number of regio-isomers in S-APM-CBA is confirmed by the H-1 NMR and HPLC measurements and theoretical calculation. Compared to the R-APM-CBA-based device with a J(sc) of 6.63 mA/cm(2), an FF of 44.3% and a PCE of 2.46%, the device using S-APM-CBA yielded a much lower J(sc) of 1.48 mA/cm(2), an FF of 32.2%, and a PCE of 0.38%. Consistently, the electron-only device using S-AMP-CBA exhibited lower electron mobility than the R-AMP-CBA-based device. These results imply that the electronic shallow-trap effect ascribed to the LUMO energy variations turned out to be insignificant in the AMP-CBA system. The lower efficiency and mobility of S-AMP-CBA might due to the assumption that the most probable trans-4-III isomer in S-AMP-CBA prevents the intermolecular facial contact of fullerenes, thereby hindering the electron transporting. Furthermore, the nanomorphology of S-AMP-CBA and R-AMP-CBA active layers could be different because of their different three-dimensional structures. This research demonstrated that steric effect of regio-isomers in a given C-60 bis-adduct is more crucial than electronic shallow-trap effect.
Suppressed piezoelectric polarization in single InGaN/GaN heterostructure nanowires
(2013-10-28)
Tsai, Wen-Che
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Chen, Yen-Ting
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Lin, Chia-Hsien
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Hsu, Wei-Ting
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Hsu, Yung-Sheng
The optical properties of single InGaN/GaN heterostructure nanowires (NWs) with a mean diameter down to 18 nm are investigated. Sharp emission lines originating from the recombination of localized excitons in the InGaN disk layer can be resolved. Excitation-dependent energy shifts, together with spectral diffusions of these emission lines, indicate the presence of a weak quantum confined Stark effect (QCSE) caused by nearby charge fluctuations, rather than the screening of piezoelectric polarizations at the InGaN/GaN interface. The absence of a piezoelectric polarization field is further confirmed by time-resolved photoluminescence measurements. Numerical simulations reveal that the elastic strain relaxation via the NW geometry is marginal and occurs only near the NW sidewalls. Carrier localization preferentially near the periphery of the InGaN disk and alloy intermixing are suggested as possible reasons for the absence of a polarization-induced QCSE in thin InGaN/GaN heterostructure NWs.
Switching Behavior and Forward Bias Degradation of 700V, 0.2A, beta-Ga2O3 Vertical Geometry Rectifiers
(2019-01-30)
Yang, Jiancheng
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Fares, Chaker
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Ren, Fan
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Chen, Yen-Ting
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Liao, Yu-Te
We report the switching recovery characteristics of large area (contact dimension 0.04 x 0.04 cm(2)) vertical geometry beta-Ga2O3 Schottky rectifiers, consisting of Si-doped epitaxial layers on conducting bulk substrates. Devices that were switched from forward current of 0.225 A to reverse off-state voltage of -700 V in an inductive load test circuit showed a recovery time (t(rr)) of 82 ns, with a reverse recovery current (I-rr) of 38 mA and dI/dt of -2.28 A. mu sec(-1). This shows the potential of Ga2O3 rectifiers for power switching applications, provided effective thermal management schemes can be implemented. Devices deliberately tested to failure under forward bias conditions exhibit delamination and cracking of the Ni/Au contact and underlying epitaxial Ga2O3 due to the low thermal conductivity of the Ga2O3. This failure mode is different to that under high reverse breakdown conditions, where pits formed by material failure under the high field generated at the edge of the rectifying contact occurs. (C) The Author(s) 2019. Published by ECS.
Synthesis and Molecular Properties of Tricyclic Biselenophene-Based Derivatives with Nitrogen, Silicon, Germanium, Vinylidene, and Ethylene Bridges
(2014-11-07)
Pao, Yu-Chieh
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Chen, Yung-Lung
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Chen, Yen-Ting
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Cheng, Sheng-Wen
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Lai, Yu-Ying
A new class of biselenophene-based materials including an sp(3)-silicon-bridged diselenosilole (DSS), an sp(3)-germanium-bridged diselenogermole (DSG), and an sp(3)-nitrogen-bridged diselenopyrrole (DSP) as well as an sp(2)-vinylidene-bridged dicyanodiselenofulvene (CDSF), a diacetylenediselenofulvene (ADSF), and a dioctylethylene-bridged benzodiselenophene (BDS) have been successfully synthesized and characterized. The bridging moieties play an important role in determining the optical and electrochemical properties. The six brominated derivatives are ready to construct various biselenophene-based conjugated materials with tunable properties for organic photovoltaics and field effect transistors.
TET1 Suppresses Cancer Invasion by Activating the Tissue Inhibitors of Metalloproteinases
(2012-09-01)
Hsu, Chih-Hung
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Peng, Kai-Lin
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Kang, Ming-Lun
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Chen, Yi-Ren
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Yang, Yu-Chih
Tumor suppressor gene silencing through cytosine methylation contributes to cancer formation. Whether DNA demethylation enzymes counteract this oncogenic effect is unknown. Here, we show that TET1, a dioxygenase involved in cytosine demethylation, is downregulated in prostate and breast cancer tissues. TET1 depletion facilitates cell invasion, tumor growth, and cancer metastasis in prostate xenograft models and correlates with poor survival rates in breast cancer patients. Consistently, enforced expression of TET1 reduces cell invasion and breast xenograft tumor formation. Mechanistically, TET1 suppresses cell invasion through its dioxygenase and DNA binding activities. Furthermore, TET1 maintains the expression of tissue inhibitors of metalloproteinase (TIMP) family proteins 2 and 3 by inhibiting their DNA methylation. Concurrent low expression of TET1 and TIMP2 or TIMP3 correlates with advanced node status in clinical samples. Together, these results illustrate a mechanism by which TET1 suppresses tumor development and invasion partly through downregulation of critical gene methylation.
Visible light communications for the implementation of internet-of-things
(2016-06-01)
Chen, Chia-Wei
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Wang, Wei-Chung
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Wu, Jhao-Ting
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Chen, Hung-Yu
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Liang, Kevin
It is predicted that the number of internet-of-things (IoT) devices will be >28 billion in 2020. Due to the shortage of the conventional radio-frequency spectrum, using visible light communication (VLC) for IoT can be promising. IoT networks may only require very low-data rate communication for transmitting sensing or identity information. The implementation of a VLC link on existing computer communication standards and interfaces is important. Among the standards, universal asynchronous receiver/transmitter (UART) is very popular. We propose and demonstrate a VLC-over-UART system. Bit error rate analysis is performed. Different components and modules used in the proposed VLC-over-UART system are discussed. Then, we also demonstrate a real-time simultaneous temperature, humidity, and illuminance monitoring using the proposed VLC link. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)