Browsing by Author "Lin, P"

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A.c. powder electroluminescence devices using ZnGa2O4 : Mn phosphor
(1998-04-01)
Yu, CF
;
Lin, P
;
材料科學與工程學系
;
電子工程學系及電子研究所
;
Department of Materials Science and Engineering
An intelligent GGSN dispatching mechanism for UMTS
(2005-05-16)
Cheng, SM
;
Lin, P
;
Tu, GH
;
Fu, LC
;
Liang, CF
3GPP proposed the Universal Mobile Telecommunication System (UMTS) to provide high-speed wireless transmission services to mobile users. To efficiently route the packets, the PDP contexts are maintained in the UE, SGSN, and GGSN in the UMTS network. Before beginning a session, the PDP Context Activation procedure is exercised to create the PDP contexts, where the SGSN selects one GGSN to serve the UE based on an IP list (for all GGSNs that can serve the UE). If the selected GGSN does not accept the request due to exception events, the SGSN chooses another GGSN until the list is exhausted, which may cause unbalance-loaded GGSNs, redundant traffic load to the network, introduce delay for the PDP context activation procedure, and thus decrease QoS for the UNITS network. To resolve the above issues, this paper proposes an intelligent GGSN dispatch mechanism 'IGD' with different sorting algorithms. The proposed mechanism is considered practical and easily installed in the existing UMTS network. We also conduct simulation experiments to investigate the performance of the IGD mechanism. (c) 2004 Elsevier B.V. All rights reserved.
Aqueous tape casting of microwave ceramic BaO center dot La2O3 center dot 4.7TiO(2)
(1998-12-01)
Lee, CC
;
Lin, P
;
材料科學與工程學系
;
Department of Materials Science and Engineering
An aqueous-based slip for tape-casting BaO . La2O3. 4.7TiO(2) ceramic sheets was studied that is suitable for substrates of microwave devices. Two separate dispersants, Na4P2O7 (S2) and CH3(CH2)(4)SO3Na, combined with poly(vinyl alcohol) and poly(ethylene glycol), were used as slip additives. The zeta potential, particle size distribution, viscosity (of the slip), tensile strength and density (of green tapes), sintered density, microstructures and microwave dielectric properties (of sintered substrates) were characterized, and their dependence on the additives were analysed. S2 shows a better dispersion function and leads to a higher density of the tapes. During the sintering, the S2 liquid on grain boundaries hindered the grain growth and the formation of second phase. The dispersant-dependent microstructures of the substrates show strong influences on the dielectric properties.
Aqueous tape casting of microwave ceramic BaO center dot La2O3 center dot 4.7TiO(2)
(1998-12-01)
Lee, CC
;
Lin, P
;
材料科學與工程學系
;
Department of Materials Science and Engineering
An aqueous-based slip for tape-casting BaO . La2O3. 4.7TiO(2) ceramic sheets was studied that is suitable for substrates of microwave devices. Two separate dispersants, Na4P2O7 (S2) and CH3(CH2)(4)SO3Na, combined with poly(vinyl alcohol) and poly(ethylene glycol), were used as slip additives. The zeta potential, particle size distribution, viscosity (of the slip), tensile strength and density (of green tapes), sintered density, microstructures and microwave dielectric properties (of sintered substrates) were characterized, and their dependence on the additives were analysed. S2 shows a better dispersion function and leads to a higher density of the tapes. During the sintering, the S2 liquid on grain boundaries hindered the grain growth and the formation of second phase. The dispersant-dependent microstructures of the substrates show strong influences on the dielectric properties.
Channel allocation for GPRS
(2001-03-01)
Lin, P
;
Lin, YB
;
資訊工程學系
;
Department of Computer Science
Based on the GSM radio architecture, general packet radio service (GPRS) provides users data connections with variable data rates and high bandwidth efficiency, In GPRS service, allocation of physical channels is flexible, i.e., multiple channels can be allocated to a user, In this paper, we propose four algorithms for the GPRS radio resource allocation: fixed resource allocation (FRA), dynamic resource allocation (DRA), fixed resource allocation with queue capability (FRAQ), and dynamic resource allocation with queue capability (DRAQ), We develop analytic and simulation models to evaluate the performance for these resource allocation algorithms in terms of the acceptance rate of both GPRS packet data and GSM voice calls. Our study indicates that DRAQ (queuing for both new and handoff calls) outperforms other algorithms.
Channel assignment for GSM half-rate and full-rate traffic
(2000-03-01)
Lin, P
;
Lin, YB
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資訊工程學系
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Department of Computer Science
Global System for Mobile Communications (GSM) supports full-rate and half-rate calls. In this paper, we propose analytical and simulation models to study the performance of four channel assignment schemes for GSM half-rate and full-rate traffic. Our study indicates that among the four schemes, the repacking scheme has the best performance for mixing half-rate and full-rate traffic. We also observe that good performance is expected if the standard derivation of the cell residence time for a mobile station is large. (C) 2000 Elsevier Science B.V. All rights reserved.
Characteristics and electrochemical performance of supercapacitors with manganese oxide-carbon nanotube nanocomposite electrodes
(2005)
Lee, CY
;
Tsai, HM
;
Chuang, HJ
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Li, SY
;
Lin, P
Supercapacitor characteristics of manganese oxide/nickel (MnOx/Ni) and manganese oxide/carbon nanotubes/nickel (MnOx/CNTs/Ni) nanocomposite electrodes were investigated in this study. The CNTs were deposited on the Ni substrate by electrophoresis in a 0.5 mg CNT/1 mL dimethylformamide solution, whereas the MnOx were synthesized by anodic deposition in a 0.16 M manganese sulfate pentahydrate aqueous solution on substrates. The crystallinity and surface morphology of these electrodes were determined by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The capacitive properties of these electrodes were demonstrated by cyclic voltammetry with scan rates ranging from 5 to 100 mV/s. The specific capacitances of the MnOx/CNT/Ni nanocomposite electrode were 415 and 388 F/g with scan rates of 5 and 100 mV/s, respectively. After 1000 cycles of operation, this electrode can maintain 79% of its original capacitance. These MnOx/CNT/Ni nanocomposite electrodes possessing good electrochemical reversibility and high capacitance may be appropriate for supercapacitor application in the future. (c) 2005 The Electrochemical Society.
Chemical solution deposition of Zn1-xZrxO thin films as active channel layers of thin-film transistors
(2006)
Lee, JH
;
Lin, P
;
Ho, JC
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Lee, CC
;
材料科學與工程學系
Sol-gel derived Zn1- xZrxO films and thin-film transistors (TFTs) were investigated in this study, where x ranges from 0.00 to 0.10. The effects of the Zr additive on the crystallinity, grain size, and surface morphology of Zn1- xZrxO films are discussed. Zn1- xZrxO-TFTs exhibited much lower off-state current (I-OFF) and higher on/off ratio than pure ZnO-TFT. The behavior of I-OFF related to the carrier concentration (n) of Zn1-xZrxO films and the correlation between n and the grain size are interpreted. The optimized I-OFF and on/off ratio of Zn1- xZrxO-TFT were 3.24 x 10(-13) A/mu m and 8.89 x 10(6) where x = 0.03, respectively. (c) 2006 The Electrochemical Society.
Credit allocation for UMTS prepaid service
(2006-01-01)
Lin, P
;
Lin, YB
;
Gan, CH
;
Jeng, JY
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資訊工程學系
Prepaid phone service requires a user to make payment before calling. In 2.5G or the 3G networks, a user may be engaged in multiple voice and/or data prepaid sessions at the same time. For such services, it is important to distribute appropriate amounts of prepaid credit units to simultaneously executed sessions of a user. By considering the universal mobile telecommunication system (UNITS) as an example, this paper studies the prepaid credit allocation for the prepaid sessions. To simulataneously accommodate more prepaid sessions for a user, we propose a credit reclaim mechanism called prepaid credit reclaim (PCR). Analysis and simulation experiments are conducted to investigate the performance of our mechanism. Our study indicates that PCR can significantly improve the-performance of the prepaid mechanism.
Effect of atmosphere on growth of single crystal zinc oxide nanowires
(2004-08-01)
Li, SY
;
Lin, P
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Lee, CY
;
Tseng, TY
;
材料科學與工程學系
Single crystal zinc oxide (ZnO) nanowires were prepared by using enhanced two-step vapor-liquid-solid (VLS) growth mechanism. The experimental results indicate that the growth rate and morphologies of the nanowires depends on the carrier gas ambient during the thermal reaction process. The ZnO nanowire grown with N-2, not only has the smaller diameter of about similar to 30 nm but also exhibits a higher growth rate and larger number of density of nanowires per unit area than those grown with Ar. The photoluminescence measurements show that the ZnO nanowires grown with N-2 have a stronger ultraviolet emission than those grown with Ar. (C) 2004 Kluwer Academic Publishers.
Effect of bismuth content on the properties of Sr0.8BixTa1.2 Nb0.9O9+y ferroelectric thin films
(1999-01-15)
Tsai, HM
;
Lin, P
;
Tseng, TY
;
材料科學與工程學系
;
電子工程學系及電子研究所
This study investigates the effect of bismuth content on the ferroelectric properties of Sr0.8BixTa1.2Nb0.9O9+y (SBTN, x = 1.7, 2.0, 2.5, 2.7, 2.9, and 3.2) thin film capacitors. SBTN films are in situ grown on Pt/SiO2/Si substrates by using two-target off-axis radio-frequency magnetron sputtering at a substrate temperature of 600 degrees C. The films are crystallized with a high (115) diffraction intensity and exhibit a columnar microstructure. Experimental results indicate that the root mean square surface roughness of the film increases with an increase of the bismuth content. In addition, the ferroelectric properties of the films heavily rely on the bismuth content. Moreover, the 440-nm-thick Sr0.8Bi2.5Ta1.2Nb0.9O9+y films exhibit maximum remanent polarization (2Pr) of 52 mu C/cm(2) and minimum coercive field (2Ec) of 28 kV/cm at an applied voltage of 1.5 V. X-ray photoelectron spectral studies reveal that except for Bi+3, no lower valence state bismuth exists in the Sr0.8Bi2.5Ta1.2Nb0.9O9+y film and bismuth substituted in the strontium site still remains in its +3 valence state. (C) 1999 American Institute of Physics. [S0021-8979(99)06302-1].
Effect of glass addition on microwave properties of BaO center dot La2O3 center dot 4.7TiO(2)
(1998-11-01)
Lee, CC
;
Lin, P
;
材料科學與工程學系
;
Department of Materials Science and Engineering
The effects of the addition of glass to the microwave properties of BaO . La2O3. 4.7TiO(2) ceramics were investigated. Three commercial glasses. PbO-B2O3-SiO2 (GA9), ZnO-B2O3-SiO2 (GP032) and PbO-Ba2O3 (LS3081), were investigated in this study. The ceramics without glass addition and sintered at 1300 degrees C gave the relative dielectric constant epsilon(r) = 92, quality factor Q = 1653 and temperature coefficient of resonant frequency tau(f) = 40.3 ppm/degrees C at 3.0 GHz. With 20 wt% GA9 addition. highly dense samples (void fraction were less than or equal to 2.5 vol%) were obtained at T, greater than or equal to 900 degrees C and their microwave properties were: epsilon(r) greater than or equal to 64, Q greater than or equal to 1037 and tau(f) less than or equal to 15.3 ppm/degrees C at 3.0 GHz. The high sintering temperature increased epsilon(r) and Q values but decreased the value of tau(f). The densification of specimens was found to play an important role in improving the dielectric constant. Heterogeneous interfaces and the dissolution of trace amounts of ceramics in glass increased the dielectric loss significantly; also, the former increased tau(f) whereas the latter decreased it.
Effect of phosphorus dopant on photoluminescence and field-emission characteristics of Mg0.1Zn0.9O nanowires
(2006-01-15)
Lee, CY
;
Tseng, TY
;
Li, SY
;
Lin, P
;
材料科學與工程學系
The photoluminescence and field-emission properties of Mg0.1Zn0.9O nanowires (MZO NWs) hydrothermally grown on the p-type silicon (100) substrates with and without phosphorus dopant were investigated in this study. Parts of MZO NWs were treated with PH3 plasma to form phosphorus-doped MZO NWs (PMZO NWs). The MZO and PMZO are wurtzite single crystals, and the surface morphologies of MZO NWs are identical to those of PMZO NWs with an average diameter of 50 nm and a length of 500 nm. The direct band gaps and emitted ultraviolet photoluminescences of the MZO and PMZO NWs are 3.41 eV and 403.8 nm and 3.56 eV and 385.4 nm, respectively. The MZO NWs grown on Si substrates have an emission threshold electric field of 1.8 V/mu m (current density of 1.0 mA/cm(2)) and a field enhancement factor, beta, of 3048 while the PMZO NWs show enhanced properties with a threshold electric field of 1.5 V/mu m and a beta value of 3054. These field-emission properties are also enhanced by illumination, which reveals that the emission behavior is affected by the surface charge state. Therefore, it is suggested that the band structure of MZO NWs has been modulated by phosphorus incorporation. (c) 2006 American Institute of Physics.
Effect of Sn dopant on the properties of ZnO nanowires
(2004-08-21)
Li, SY
;
Lin, P
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Lee, CY
;
Tseng, TY
;
Huang, CJ
Sri doped ZnO (SZO) nanowires were fabricated by a vapour-liquid-solid growth process. The reaction temperature for the formation of the nanowires can be reduced to similar to100degreesC due to Sri doping. The growth direction and morphology of SZO nanowires depend on the amount of Sn, which is attributed to the difference in sizes between Zn and Sri atoms. The ultraviolet emission of SZO nanowires varies from 380 to 396 nm since Sri acts as a doubly ionized donor and introduces deep states in the band gap. In addition, the SZO nanowires exhibit significantly Improved field emission characteristics with a turn-on electric field of 0.05 V mum(-1) under a current density of 0.5 mA cm(-2) in comparison with undoped ZnO nanowires. The work function of the SZO nanowire decreases for higher carrier concentrations and the field enhancement factor increases for smaller diameters. Also, the resistance of the SZO nanowire is decreased for the higher Sri mole fraction. Therefore, it is expected that SZO nanowires can be applied in nano-lasers and flat panel displays in the future.
Effects of glass additions on microstructure and microwave dielectric properties of La4Ti9O24 ceramics
(2005-07-15)
Liu, YW
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Lin, P
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材料科學與工程學系
;
Department of Materials Science and Engineering
Two commercially available glasses, PbO-B2O3-SiO2 (GA-9) and ZnO-B2O3-SiO2 (GP-032), were used to improve the sintering property of La4Ti9O24 ceramics. Above 20 vol.% of respective GA-9/GP-032 addition, La4Ti9O24 ceramics with similar to 95% of the theoretical density were obtained at a relatively low temperature of similar to 1000 degrees C, compared to the sintering temperature, similar to 1350 degrees C, for preparing pure La4Ti9O24 bulks with a similar density. The interaction between GA-9 and La4Ti9O24 results in the formation of a secondary phase La2/3TiO3. Further investigations indicated that La2/3TiO3 has a strong influence on the microwave dielectric property of La4Ti9O24 ceramics with GA-9 addition. (c) 2005 Elsevier B.V. All rights reserved.
Effects of glass additions on microstructure and microwave dielectric properties of La4Ti9O24 ceramics
(2005-07-15)
Liu, YW
;
Lin, P
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Two commercially available glasses, PbO-B2O3-SiO2 (GA-9) and ZnO-B2O3-SiO2 (GP-032), were used to improve the sintering property of La4Ti9O24 ceramics. Above 20 vol.% of respective GA-9/GP-032 addition, La4Ti9O24 ceramics with similar to 95% of the theoretical density were obtained at a relatively low temperature of similar to 1000 degrees C, compared to the sintering temperature, similar to 1350 degrees C, for preparing pure La4Ti9O24 bulks with a similar density. The interaction between GA-9 and La4Ti9O24 results in the formation of a secondary phase La2/3TiO3. Further investigations indicated that La2/3TiO3 has a strong influence on the microwave dielectric property of La4Ti9O24 ceramics with GA-9 addition. (c) 2005 Elsevier B.V. All rights reserved.
Effects of oxygen-argon mixing on the electrical and physical properties of ZrTiO4 films sputtered on silicon at low temperature
(1995-12-15)
Chang, DA
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Lin, P
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Tseng, TY
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材料科學與工程學系
;
電子工程學系及電子研究所
Zirconium titanate (ZrTiO4) thin films (200-260 nm) on p-type (100) Si substrates were prepared using radio-frequency sputter deposition at room temperature in atmosphere of various O-2/Ar mixing ratio (from 0/100 to 20/80). All films exhibited a (020) preferred orientation and small grain size with increasing O-2/Ar ratio, as shown by x-ray diffraction. The variations of dielectric constant, fixed oxide charge, and interface trapped charge with O-2/Ar ratio are studied with an Al/ZrTiO4/Si structure. The refractive index and dielectric constant varied in ranges 2.34-2.26 and 20-16 for the as-deposited films. Within the range investigated, crystallinity appears to have a stronger influence on the densities of charge-trapping centers in the films than oxygen stoichiometry, and the latter may determine the leakage current density. A remarkable two orders of magnitude decrease in leakage current to 5.6X10(-9) A/cm(2) at 0.1 MV/cm and an increase in breakdown field beyond 1.2 MV/cm are observed in the film deposited without oxygen after a 400 degrees C annealing in air for 1 h. The current transport in ZrTiO4 film is dominated by the Poole-Frenkel mechanism. (C) 1995 American Institute of Physics.
Electrical characterizations of a controllable field emission triode based on low temperature synthesized ZnO nanowires
(2006-01-14)
Lee, CY
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Tseng, TY
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Li, SY
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Lin, P
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材料科學與工程學系
Fabrication and field emission properties of a ZnO nanowire (NW) triode were investigated in this study. The ZnO NWs have a single-crystalline wurtzite structure, similar to 50 nm diameter and 3.4 x 10(10) cm(-2) number density. The ZnO NW triode shows good and controllable emission properties with the turn-on anode electric field (at a current density of 1 mu A cm(-2)), threshold anode electric field (at a current density of 1 mA cm(-2)) and field enhancement factor of 1.6, 2.1 V mu m(-1) and 3340, respectively. The ZnO NW triode exhibits transistor characteristics with a gate leakage region, linear region and saturation region. Furthermore, the controllable field emission performance of the ZnO NW triode can be enhanced by illumination and argon ion bombardment. A low temperature Si-based microelectronic compatible fabrication process was provided for successfully making ZnO NW based triodes with good field emission properties.
Electrical properties and crystal structure of (Ba,Sr)TiO3 films prepared at low temperatures on a LaNiO3 electrode by radio-frequency magnetron sputtering
(1997-01-13)
Chu, CM
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Lin, P
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材料科學與工程學系
;
Department of Materials Science and Engineering
(Ba,Sr)TiO3 films on a LaNiO3 underlayer were prepared by radio-frequency magnetron sputter deposition. The onset of crystallization of the films occurred at a deposition temperature (T-d) as low as 200 degrees C. Good crystallinity was observed at T-d greater than or equal to 350 degrees C. A moderate high dielectric constant (epsilon(r) similar to 170-250) of the films was obtained at relatively low T-d similar to 200-360 degrees C. The value of epsilon(r) showed a much slower increase with T-d greater than or equal to 350 degrees C than that expected from the progress of crystallinity. The deviation was attributed to an interdiffusion layer formed between the him and underlayer, which also caused an abnormal contact potential barrier and a decline of the epsilon(r) value of the samples postannealed at 350 degrees C. Annealing at 300 degrees C under O-2 atmosphere lessened the oxygen deficiency in the film and enhanced the dielectric constant without forming an interfacial layer. (C) 1997 American Institute of Physics.
Electrical properties and crystal structure of (Ba,Sr)TiO3 films prepared at low temperatures on a LaNiO3 electrode by radio-frequency magnetron sputtering
(1997-01-13)
Chu, CM
;
Lin, P
;
材料科學與工程學系
;
Department of Materials Science and Engineering
(Ba,Sr)TiO3 films on a LaNiO3 underlayer were prepared by radio-frequency magnetron sputter deposition. The onset of crystallization of the films occurred at a deposition temperature (T-d) as low as 200 degrees C. Good crystallinity was observed at T-d greater than or equal to 350 degrees C. A moderate high dielectric constant (epsilon(r) similar to 170-250) of the films was obtained at relatively low T-d similar to 200-360 degrees C. The value of epsilon(r) showed a much slower increase with T-d greater than or equal to 350 degrees C than that expected from the progress of crystallinity. The deviation was attributed to an interdiffusion layer formed between the him and underlayer, which also caused an abnormal contact potential barrier and a decline of the epsilon(r) value of the samples postannealed at 350 degrees C. Annealing at 300 degrees C under O-2 atmosphere lessened the oxygen deficiency in the film and enhanced the dielectric constant without forming an interfacial layer. (C) 1997 American Institute of Physics.