Browsing by Author "Cheng, TY"

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A broadband and low cost monolithic BiCMOS tuner chip
(2004-11-01)
Chen, YH
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Cheng, TY
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Chang, CY
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交大名義發表
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National Chiao Tung University
This circuit is a single chip of a BiCMOS wafer used in cable TV set-top converters;, cable modems, cable TV tuners and digital TVs. It is a double conversion tuner (DCT) structure which has better performance characteristics than the single conversion tuner (SCT). This single chip comprises two LNAs, one AGC, two LO buffers, two VCOs, two resistor-type and double-balanced Gilbert cell mixers, two synthesizers and ESD protection. Its total gain is 45.70 dB, and its total noise figure is 4.3-7.9 dB. The RF varied range, which is not only 50-860 MHz but also 50-1000 MHz, can be applied in cable TV tuners and cable modems. The consuming power is 0.885 W under 3 V and the die size is 4.8 mm(2).
Chemical vapor deposition of zinc oxide thin films on Y2O3/Si substrates
(2004)
Lin, CW
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Cheng, TY
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Chang, L
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Juang, JY
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材料科學與工程學系
Highly-oriented ZnO films were deposited on Y2O3/Si(111) and Y2O3/Si(100) substrates by atmospheric pressure metal-organic chemical vapor deposition (MOCVD) using zinc acetylacetonate (Zn(C5H7O2)(2)) and oxygen as sources. The substrate temperature and O-2 gas temperature were all kept at 500 degreesC. Y2O3, thermodynamically more stable than SiO2 and epitaxially formed on Si, is used as buffer layer. Epitaxial Y2O3 of 200 nm thickness were first grown by pulsed laser deposition on Si(111) and Si(100) substrates at 800 degreesC for 30 min. X-ray diffraction patterns of the samples only show sharp diffraction peaks of Y2O3{222} and ZnO{0002}. The photoluminescence spectra of ZnO show strong peaks of near the band edge and very weak peaks of deep-level emission at 7 K and room temperature. Cross-sectional transmission electron microscopy shows that the highly-oriented ZnO films has columnar structure with a grain size distribution of 600-850 Angstrom. Most of ZnO grains exhibit orientation relationship with Y2O3 as {0002}(ZnO)//{222}(Y2O3), <0110>(ZnO)//(112)(Y2O3), and <1120>(ZnO)//<110>(Y2O3). (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA. Weinheim.
Superconducting NdBa2Cu3O7-delta thin films grown on bare (1(1)over-bar02) sapphire by pulsed laser deposition
(2003-05-01)
Cheng, TY
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Lin, PI
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Chen, SF
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Liu, SJ
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Juang, JY
Superconducting NdBa2Cu3O7-delta (NBCO) thin films with T-c=89 K have been. successfully grown on bare (1 (1) over bar 02) sapphire substrates by pulsed laser deposition (PLD). The X-ray diffraction results show that the as-grown NBCO films are all c-axis oriented with no observable second phase. The c-axis parameter decreases monotonically with increasing the deposition temperature (T-s), suggesting that the corresponding degradation of T-c for T-s>790degreesC might not originate from oxygen deficiency. It is conceived that the film-substrate reaction that occurring at the interface may cause Ba-deficiency and hence enhance Nd-Ba antisite substitutions.
The magneto-transport properties of epitaxial La0.7Sn0.3MnO3 manganite thin films
(2005-08-01)
Cheng, TY
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Hsieh, CC
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Juang, JY
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Lin, JY
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Wu, KH
Single-phase La0.7Sn0.3MnO3 (LSnMO) thin films were fabricated on SrTiO3 (STO) substrates by pulsed laser deposition (PLD). The as-deposited films, though were insulating with no sign of insulator-metal transition (IMT), did display paramagnetic-ferromagnetic transition (PFT) around 150 K. Ex situ annealing of the films at 850 degrees C in 250 Torr oxygen for 4 h, nonetheless, not only significantly improves the crystallographic quality but also raises IMT and PFT at 315K and 320K, respectively. The manifestations of spin-glass-like behavior in both the as-deposited and postannealed films suggest that it could be intrinsic LSnMO, albeit transport properties can be drastically changed by the strain originating from large ion-size misfit between Sn and La and film/substrate epitaxial relation. The preliminary X-ray absorption spectroscopy shows signature of Mn3+/Mn2+ mixed-valence indicating that tetravalent Sn ions does result in electron-doping into the e, band of Mn. (c) 2005 Elsevier B.V. All rights reserved.