Browsing by Author "Lin, IN"

Now showing 1 - 16 of 16

Effect of catalyst on growth behavior of carbon nanotube synthesizing by microwave heating thermal chemical vapor deposition process
(2001-05-01)
Chen, SC
;
Shih, LY
;
Chang, YC
;
Tu, GC
;
Lin, IN
A modified chemical vapor deposition process, which utilizes a susceptor to absorb the microwave and to self generate the heat, for heating up the Si substrate, was used for growing carbon nanotubes (CNTs). The advantage of such a process is that the deposition chamber can be maintained at around room temperature with only the substrates localized heated, such that the deposition temperature can be more precisely controlled. The influence of the pretreatment process for catalyst-coated Si substrates on growth behavior of CNTs and the related electron field emission properties were systematically examined. Among the form of catalyst used, the Fe(NO3)(3)-ethythersilicate mixture performs much better than the de sputtered Fe films. The higher the concentration of Fe species in the catalyst mixture, the denser the CNTs formed on the subs;rates, resulting in better held emission properties. Thus grown CNTs can be turned on at a very low field (E(0)congruent to0.78 V/mum), achieving a very large emission current density (J(e)congruent to 13 mA/cm(2)) at 5.5 V/mum applied field. (C) 2001 American Vacuum Society.
Effects of composition on low temperature sinterable Ba-Nd-Sm-Ti-O microwave dielectric materials
(2004)
Cheng, CC
;
Hsieh, TE
;
Lin, IN
;
材料科學與工程學系
;
Department of Materials Science and Engineering
This work investigated the effects of MgO and ZnO additives on the microwave properties of BRT114 = [(BaO.R2O3.4TiO(2)).0.06(2Bi(2)O(3).3TiO(2))] materials. Incorporation of small amount of ZnO (less than or equal to1 wt.%) markedly lowered the temperature coefficient of resonant frequency (tau(f)), to around tau(f) = 1 ppm/degreesC, slightly increased the density and dielectric constant (epsilon(r)) of the materials, but degraded the Q x f factor. Doping 2.5 mol% of MgO, in addition to ZnO, further improved the tau(f)-value for the BRT114 materials. The dielectric constant and the Q x f factor of the materials degrade pronouncedly when doped with too abundant ZnO. Microstructure and EDX analyses indicated that the main factor for degrading the microwave properties is the induction on formation of secondary phases. Moreover, sol gel and fused Ba-B-Si glass reacted with BRT114 in quite a different way. Fused glass wets BRT114 materials more easily than the sol-gel derived glass, resulting in composite materials with higher density and larger dielectric constant. Precalcining the glass-dielectrics mixture, greatly improved the wetting ability of the glass and markedly increased the microwave properties of the glass/dielectric composite, i.e. LTCC materials. (C) 2003 Elsevier Ltd. All rights reserved.
Electrical properties of ZnO varistors prepared by microwave sintering process
(1996-09-01)
Chen, CS
;
Kuo, CT
;
Lin, IN
;
機械工程學系
;
材料科學與工程學系
Microwave sintering processes were observed to substantially enhance the densification rate for ZnO varistor materials. Samples microwave sintered at 900-1200 degrees C for 10 min reached the same high density as those conventionally sintered at the same temperature for 60 min. A similar tendency was observed for the grain size. Prolonged microwave sintering, however, resulted in fast grain growth and degraded electric field-current density (E-J) properties. Capacitance-voltage (C-V) analysis indicated that the degradation in E-J behavior primarily resulted from the decrease in grain boundary barrier height. The modification of the grain boundary electrical properties, in turn, is ascribed to the loss of volatile Bi species along the grain boundaries.
Formation of carbon cluster on the surface of diamond films for improving electron field emission properties
(2002-10-01)
Chang, YC
;
Tu, JC
;
Kuo, CT
;
Wang, CY
;
Lin, IN
The electron field emission properties of the diamond films were significantly improved via the formation of nanosized carbon clusters on their surface. The microstructures and Raman spectroscopy are markedly altered when the diamond films were coated with a thin layer of Fe/Co films (< 10 nm) and then post-annealed at high enough temperature ( > 800degreesC). The turn-on field was decreased from 14.8 to 7.6 V/mum and the electron field emission current density was increased more than 2 order of magnitude, from 20 to 2400 muA/cm(2), due to post-annealing process. (C) 2002 Elsevier Science B.V. All rights reserved.
Growth and fatigue properties of pulsed laser deposited Pb1-xLax(ZryTiz)O-3 thin films with [001] preferred orientation
(1996-12-01)
Lin, WJ
;
Tseng, TY
;
Wu, YZ
;
Lin, SP
;
Tu, SL
Growth of [00/] preferentially oriented Pb1-xLax(ZryTiz) O-3 (PLZT) thin films was carried out by using targets of either tetragonal or rhombohedral structure. The tetragonal films grew in a similar manner to the rhombohedral films. Both the substrate temperature (500 or 550 degrees C) and oxygen pressure (0.1 mbar, 10 Pa) required stringent control in order to deposit [00/]-textured PLZT thin films. The ferroelectric and fatigue properties were examined. The films deposited on YBa2Cu3O7-x and CeO2 coated silicon (YBCO/CeO2/Si) substrates possessed substantially lower remanent polarization than those grown on YBCO coated SrTiO3 (YBCO/STO) substrates; this is ascribed to inferior crystallinity of the PLZT/BCO/CeO2/Si films. The remanent polarization of tetragonal PLZT films was degraded insignificantly up to 10(8) polarization switching cycles, whereas that of rhombohedral PLZT films was already reduced to 80% of the initial value after 10(8) cycles. Low endurance of rhombohedral films was ascribed to the periodic stress induced when the inclined spontaneous polarization vector (P=[111]) switched. On the other hand, high endurance of tetragonal films was explained by the fact that the spontaneous polarization vector (P=[001]) lies along the film's normal such that switch cycles cause no lateral stress.
Improvement on the degradation of microwave sintered ZnO varistors by postannealing
(1998-06-01)
Chen, CS
;
Kuo, CT
;
Lin, IN
;
材料科學與工程學系
;
Department of Materials Science and Engineering
The microwave sintering process not only densified the ZnO materials in a higher rate, but also resulted in significantly better varistor characteristics. Large nonlinear coefficient and low leakage current density were attained by cooling the samples under a rate of 80 degrees C/min after sintering, followed by 600 degrees C postannealing for 60 min under oxygen atmosphere. Inappropriate annealing deteriorated the varistor characteristics that can either be attributed to the insufficient reoxidation along grain boundaries when annealed in N-2 (or air) or loss of Zn species in these regions when annealed at 750 degrees C (900 degrees C). By contrast, the degradation behavior of these materials can be improved by the annealing process regardless of the annealing atmosphere or temperature.
Interdiffusion of multilayer ferroelectric thin films using YBa2Cu3O7-x as an intermediate layer
(1996-05-15)
Wang, JP
;
Ling, YC
;
Lin, IN
;
Lin, WJ
;
Tseng, TY
Interdiffusion between layers in multilayer ferroelectric thin films was studied from their elemental depth profiles using secondary ion mass spectrometry. Among the films deposited on YBa2Cu3O7-x/CeO2/Si substrates, the interdiffusion is most pronounced for [Sr0.5Ba0.5]Nb2O6(SBN) films, less marked for Pb0.97La0.03(Zr1-xTix)(0.9925)O-3 (PLZT, x=0.54 or 0.34) films, and is least significant for BaTiO3 films. Higher substrate temperature used for growing SBN films is believed to be the main cause of interdiffusion. The larger proportion of cationic vacancies existing in PLZT films is another possible source inducing interdiffusion. Using YBa2Cu3O7-x/SrTiO3 as substrates substantially reduces the interdiffusion between layers. This is ascribed to the better crystallinity of the YBa2Cu3O7-x layers deposited on SrTiO3 substrates. These results indicate that both the characteristics of ferroelectric films and the underlying YBa2Cu3O7-x layers substantially modify the interdiffusion behavior between the layers. (C) 1996 American Institute of Physics.
Microstructure and nonlinear properties of microwave-sintered ZnO-V2O5 varistors: I, effect of V2O5 doping
(1998-11-01)
Kuo, CT
;
Chen, CS
;
Lin, IN
;
材料科學與工程學系
;
Department of Materials Science and Engineering
The modification of the densification behavior and the grain-growth characteristics of the microwave-sintered ZnO materials, caused by the incorporation of V2O5 additives, have been systematically studied. Generally, the addition of V2O5 markedly enhances the densification rate, such that a density as high as 97.9% of the theoretical density and a grain size as large as 10 mu m can be attained for a sintering temperature as low as 800 degrees C and a soaking time as short as 10 min. Increasing the sintering temperature or soaking time does not significantly change the sintered density of the ZnO-V2O5 materials but it does monotonously increase their grain size. Varying the proportion of V2O5 in the range of 0.2-1.0 mol% does not pronouncedly modify such behavior. The leakage current density (J(L)) of these high-density and uniform-granular-structure samples is still large, which is amended by the incorporation of 0.3 mol% of Mn3O4 in the ZnO materials, in addition to 0.5 mol% of the V2O5 additives. Samples that are obtained using such a method possess good nonohmic characteristics (alpha = 23.5) and a low leakage current density (J(L) = 2.4 x 10(-6) A/cm(2)).
Microstructure and nonlinear properties of microwave-sintered ZnO-V2O5 varistors: I, effect of V2O5 doping
(1998-11-01)
Kuo, CT
;
Chen, CS
;
Lin, IN
;
材料科學與工程學系
;
Department of Materials Science and Engineering
The modification of the densification behavior and the grain-growth characteristics of the microwave-sintered ZnO materials, caused by the incorporation of V2O5 additives, have been systematically studied. Generally, the addition of V2O5 markedly enhances the densification rate, such that a density as high as 97.9% of the theoretical density and a grain size as large as 10 mu m can be attained for a sintering temperature as low as 800 degrees C and a soaking time as short as 10 min. Increasing the sintering temperature or soaking time does not significantly change the sintered density of the ZnO-V2O5 materials but it does monotonously increase their grain size. Varying the proportion of V2O5 in the range of 0.2-1.0 mol% does not pronouncedly modify such behavior. The leakage current density (J(L)) of these high-density and uniform-granular-structure samples is still large, which is amended by the incorporation of 0.3 mol% of Mn3O4 in the ZnO materials, in addition to 0.5 mol% of the V2O5 additives. Samples that are obtained using such a method possess good nonohmic characteristics (alpha = 23.5) and a low leakage current density (J(L) = 2.4 x 10(-6) A/cm(2)).
Microstructure and nonlinear properties of microwave-sintered ZnO-V2O5 varistors: II, effect of Mn3O4 doping
(1998-11-01)
Kuo, CT
;
Chen, CS
;
Lin, IN
;
材料科學與工程學系
;
Department of Materials Science and Engineering
The microstructure and nonlinear current-voltage characteristics of Mn3O4-doped ZnO-V2O5 ceramics, microwave-sintered at 800 degrees-1200 degrees C for 10 min, have been investigated. A high density (96% of the theoretical density) has been achieved. The incorporation of Mn3O4 additives does not significantly alter the densification behavior of the ZnO-V2O5 materials, but rather pronouncedly increases the non-linear coefficient (alpha = 23.5) and markedly suppresses their leakage current density (J(L) = 2.4 x 10(-6) A/cm(2)). On the other hand, the intrinsic properties of the materials, including the Schottky barrier height (Phi(b)) and the donor density (N-d), are only moderately modified; that is, Phi(b) = 1.16 eV and N-d = 5.4 x 10(17)/cm(3). X-ray diffractometry analyses and energy-dispersive X-ray microanalyses (via scanning electron microscopy) indicate that the V2O5 species facilitate the densification and the development of microstructure via the formation of a liquid phase (Zn-3(VO4)(2)) along the grain boundaries, whereas the Mn3O4 species markedly enhance the nonohmic behavior of the ZnO-V2O5 materials by forming the surface states along the grain boundaries.
Microstructure and nonlinear properties of microwave-sintered ZnO-V2O5 varistors: II, effect of Mn3O4 doping
(1998-11-01)
Kuo, CT
;
Chen, CS
;
Lin, IN
;
材料科學與工程學系
;
Department of Materials Science and Engineering
The microstructure and nonlinear current-voltage characteristics of Mn3O4-doped ZnO-V2O5 ceramics, microwave-sintered at 800 degrees-1200 degrees C for 10 min, have been investigated. A high density (96% of the theoretical density) has been achieved. The incorporation of Mn3O4 additives does not significantly alter the densification behavior of the ZnO-V2O5 materials, but rather pronouncedly increases the non-linear coefficient (alpha = 23.5) and markedly suppresses their leakage current density (J(L) = 2.4 x 10(-6) A/cm(2)). On the other hand, the intrinsic properties of the materials, including the Schottky barrier height (Phi(b)) and the donor density (N-d), are only moderately modified; that is, Phi(b) = 1.16 eV and N-d = 5.4 x 10(17)/cm(3). X-ray diffractometry analyses and energy-dispersive X-ray microanalyses (via scanning electron microscopy) indicate that the V2O5 species facilitate the densification and the development of microstructure via the formation of a liquid phase (Zn-3(VO4)(2)) along the grain boundaries, whereas the Mn3O4 species markedly enhance the nonohmic behavior of the ZnO-V2O5 materials by forming the surface states along the grain boundaries.
Microstructures and electrical properties of V2O5-based multicomponent ZnO varistors prepared by microwave sintering process
(1997-03-01)
Chen, CS
;
Kuo, CT
;
Wu, TB
;
Lin, IN
;
材料科學與工程學系
The V2O5-based ZnO varistor materials were successfully densified using microwave sintering process. The materials can reach a high density as 94.6% T.D. (theoretical density) when sintered at 800 degrees C (10 min) but the grain growth was initiated only when sintered at a higher temperature than 1000 degrees C (10 min). The varistor characteristics, including breakdown voltage (V-bk), nonlinear coefficient (alpha) and leakage current density (J(L)), degraded markedly for the samples sintered at too high temperature (i.e., T greater than or equal to 1000 degrees C) and for too long period (i.e., t greater than or equal to 10 min) that was ascribed to the occurrence of abnormal grain growth. Contrarily, the intrinsic characteristics, including potential barrier height (phi(b)) and donor density (N-d), varied only moderately with these sintering conditions. The V2O5-based ZnO materials sintered at 1000 degrees C (5 min) possessed good varistor characteristics as V-bk = 248 V/mm, alpha = 31 and J(L) = 4.6 x 10(-5) A/cm(2). The corresponding intrinsic parameters are phi(b) = 0.63 eV and N-d = 2.37 x 10(24) m(-3).
Microstructures and electrical properties of V2O5-based multicomponent ZnO varistors prepared by microwave sintering process
(1997-03-01)
Chen, CS
;
Kuo, CT
;
Wu, TB
;
Lin, IN
;
材料科學與工程學系
The V2O5-based ZnO varistor materials were successfully densified using microwave sintering process. The materials can reach a high density as 94.6% T.D. (theoretical density) when sintered at 800 degrees C (10 min) but the grain growth was initiated only when sintered at a higher temperature than 1000 degrees C (10 min). The varistor characteristics, including breakdown voltage (V-bk), nonlinear coefficient (alpha) and leakage current density (J(L)), degraded markedly for the samples sintered at too high temperature (i.e., T greater than or equal to 1000 degrees C) and for too long period (i.e., t greater than or equal to 10 min) that was ascribed to the occurrence of abnormal grain growth. Contrarily, the intrinsic characteristics, including potential barrier height (phi(b)) and donor density (N-d), varied only moderately with these sintering conditions. The V2O5-based ZnO materials sintered at 1000 degrees C (5 min) possessed good varistor characteristics as V-bk = 248 V/mm, alpha = 31 and J(L) = 4.6 x 10(-5) A/cm(2). The corresponding intrinsic parameters are phi(b) = 0.63 eV and N-d = 2.37 x 10(24) m(-3).
Microwave dielectric properties of glass-ceramic composites for low temperature co-firable ceramics
(2003)
Cheng, CC
;
Hsieh, TE
;
Lin, IN
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Ba-B-Si glass was added to Ba-Nd-Sm-Bi-Ti-O (BRT114) microwave dielectric material for LTCC applications. Conventional one-step processing method for preparing glass-BRT114 composite materials yields low dielectric constant, since the glass was easy to react with BRT114 and forms a low dielectric constant phase, Ba3B6Si2O16. A large proportion of pores appeared. The nature of glass, whether it is sol-gel derived or fused, shows marked influence on the microstructure and microwave dielectric properties of the composites. A two-step process containing precoating the BRT114 powders with a thin layer of glass, followed by conventional samples preparation process, tremendously improved the densification behaviour of the material. The formation of pores and interactions between glass and BRT114 was greatly suppressed such that materials with high dielectric constant (epsilon(r) = 40) were achieved by sintering 9 wt.% glass-containing composite at 950 degreesC for 2.5 h. (C) 2003 Elsevier Ltd. All rights reserved.
Modification on the surface of superconducting YBa2Cu3O7-x films by microwave plasma-enhanced pulsed laser deposition
(1995-12-15)
Huang, CS
;
Tseng, TY
;
Chung, BC
;
Tsai, CH
;
Hsu, SS
Superconducting YBa2Cu3O7-x films having smooth surfaces were successfully synthesized by a microwave plasma-enhanced pulsed laser deposition (PEPLD) process. Particulates that frequently occurred in films grown by the conventional PLD process were effectively eliminated. The films were epitaxial-like. The c-axis was perpendicular to the films' surface, the a and b axes were aligned in the films' plane, and the onset and zero of the transition temperature were at T-c=90 K and T-c0=86 K, respectively. Optical emission spectroscopy indicated that the presence of oxygen plasma not only reexcited the laser-induced species via the collision process, but also produced abundant atomic oxygen in PEPLD process. The surface reaction kinetics for the formation of the thin-film process was thus greatly enhanced, which substantially improved the thin-film quality. (C) 1995 American Institute of Physics.
The effect of composition on Ba-Nd-Sm-Ti-O microwave dielectric materials for LTCC application
(2003-04-10)
Cheng, CC
;
Hsieh, TE
;
Lin, IN
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Effect of composition of BaO.(R2O3)(y).(TiO2)(z).0.06(2Bi(2)O(3).3TiO(2)) materials, R = Nd(1-x)Sm(x),BRT, on the materials characteristics and microwave dielectric properties of the samples was systematically examined. The Ti/Ba ratio (z value) shows the most significant effect on the microwave dielectric properties of the materials. The Q x f-value is small for z less than or equal to 3.82 materials, and showing maximum value for z = 4.32 samples, then decrease for z = 4.52 composition, which is possibly due to the presence of secondary phase for Z = 3.82 and 4.52 materials. Diffusion couple experiments shows that the interaction diffusion zone between glass and BRT ceramic is not pronounced, so that Ba-B-Si glass and BRT could be a good low temperature co-firable ceramic system is inferable. (C) 2002 Elsevier Science B.V. All rights reserved.