Tunghai University Low Dimensional Science Workshop 2010 Fallezphysics.nchu.edu.tw/LDS/workshop/2010fallworkshop/LDS_information.pdf · LDS Workshop, 2010 Fall Tunghai University

LDS Workshop, 2010 FallTunghai University

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Low Dimensional Science Workshop

2010 Fall

地點: 東海大學

中華民國 99 年 12 月 12 日

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Low Dimensional Science Workshop

2010 Fall

日期 : 2010.12.12地點 : 東海大學基礎科學大樓-求真廰網址 : http://140.120.11.1/LDS/index.htm主辦單位: 東海大學物理系協辦單位: 彰化師範大學物理系

中興大學物理系東海大學奈米中心

贊助廠商:汎達科技有限公司捷東股份有限公司

聯絡人 : 簡世森技術委員 : 吳仲卿教授、孫允武教授秘書 : 王紹倩小姐

會場所在地


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III


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Program8:30~9:00

Registration

9:00~9:15Opening remark

9:15~10:15 Lecture陳啟東教授 Graphene: Basic Properties and Possible Applications

主持人: 吳小華主任

10:15~ 10:45 Coffee BreakSection A Chair: 林宗欣老師

Number Time Speaker Title

A 1*10:45 ~11:10

高貴生Highly efficiency of CdS/CdSe Quantum Dots

Co-sensitized Solar Cells

A 211:10 ~11:25

郭鴻榮

Design a Confocal Microscope for

Low-Temperature and High-Magnetic-Field

Application (II)

A 311:25 ~11:40

歐奕欣Study of Guided Mode Resonance in Silicon

Nitride Photonic Crystal Slabs

A 411:40

~11:55陶靜傑

Distribution of Germanium in SiO2/Ge/Si structure

by using scanning near-field optical microscopy

A 511:55~12:10

古硯涵Electron Beam Induced Deposition for Tip Apex

Modification

12:10 ~ 13:40 Lunch & pictureSection B Chair: 張晃暐老師


B 1*13:40 ~14:05

郭政宜Direct current effect on the Microstructured spin

valves ellipses

B 214:05 ~14:20

鄭念佳

Study of magnetization configuration and

switching behavior in submicro-scaled asymmetric

Permalloy ring

B 314:20 ~14:35

袁志瑋Structure and magnetic properties of

pulse-laser-deposited FePt films

B 414:35 ~14:50

蔡德穎Size-induced valence transition in Ce3Pt4 and

CeAuAl3 alloys

B 514:50 ~15:05

蘇于宗

Design and Test of a Measurement System using

Planar Gradiometers and Superconducting

Quantum Interference Device


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15:05~15:30 Coffee BreakSection C Chair:王昌仁老師


C 115:30 ~15:45

李宥勳Graphene Edges Identified by

Polarization-Dependent Raman Spectroscopy

C 215:45 ~16:00

林宥辰Characteristics of carbon nanotube and ZnO

nanorod field effect transistors

C 316:00 ~16:15

邱凡芸

Field Emission Characteristic of C84 imbedded

Silicon Surface Using Scanning Tunneling

Microscopy

C 416:15~16:30

王文峰Ion conduction through nanopores on silicon

nitride membrane

16:30~17:00 Closing Ceremony


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A1Highly efficiency of CdS/CdSe Quantum Dots Co-sensitized Solar Cells

Auttasit Tubtimtae (高貴生),1 Ming-Way Lee(李明威), 1and Gou-Jen Wang(王國禎)2

1Department of Physics and Institute of Nanoscience, National Chung Hsing University, Taichung,

Taiwan2Department of Mechanical Engineering and Institute of Biomedical Engineering, National Chung

Hsing University, Taichung, Taiwan

Abstract

We present a highly perform of a co-sensitizer of CdS/CdSe quantum dots with apassivation layer and heat annealing effect. Deposited-quantum-dot and passivationlayers mesoporous TiO2 film were prepared by a series of successive ionic layeradsorption and reaction (SILAR) techniques. The growth of each conditions weremonitored using UV-visible absorption spectra. It can be showed the absorption edgeof 520 nm for 150oC heating-CdS(4) and 700 nm for 300oC heating-CdSe(5). Thecharacterization of CdS/CdSe QDs were observed using high-resolution transmissionelectron microscope (HR-TEM) showed the cubic growth structure of CdS and CdSeand diameter size of a single QDs ~ 5 and 10 nm, respectively. For the photovoltaicperformance, the multicomponent photoelectrode was evaluated in a redox mediatorof polysulfide electrolyte. We observe that multi-layer of passivation and the optimumheat annealing effect can be improved an overall power conversion efficiency of4.88% using Pt-counter electrode and exceeding ~ 5% with Au-counter electrode at 1sun. The best power conversion efficiency of 5.43% yielded at 0.1 sun.


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A2

Design a Confocal Microscope for Low-Temperature and High-Magnetic-Field

Application (II)

郭鴻榮國立中興大學

We design a confocal optical microscope system for samples in a

low-temperature (4.2 K) and high-magnetic-field (14 T) environment. Due to the limit

of the conventional cryogenic dewar, this system has a very long optical path 1600

mm compared to a normal microscope and thus a very large aberration. We carefully

adjust the lens configuration to reduce the aberration and check with ZEMAX

simulation. The objective lens, which will be in the low temperature environment,

with a 50 mm focal length is composed by two plano-convex and a plano-concave

fused silica lenses. The tube lens in the optical head is made up two plano-convex

lenses and with a 200 mm focal length. The magnification of this optical system is

about four times. This system also includes a CCD to monitor the sample and the laser

beam spot, and a pinhole, which may be replaced by a fiber connected to a spectral

measurement setup. We chose red light emitted diodes (LEDs) as the light source of

the optical microscope due to the limit of wavelength of the dichroic mirror. we

placed these LEDs in a housing between the objective lens and sample. In front of the

CCD, we install a lens set to control fields of view. The sample stage includes a XY

scanner and three positioners from Attocube, and its housing is totally made of

Titanium. The preliminary results and mechanical parts will be presented.


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A3Study of Guided Mode Resonance in Silicon Nitride Photonic Crystal Slabs

Neil Ou, J. H. Shyu, H. M. Lee, and J. C. WuInstitute of Photonics, National Changhua University of Education, Taiwan

abstract

We present a study of the optical transmission characteristics through 2-D photoniccrystal slab (PCS) in the visible light region. In this experiment, a series of 100nm-thick freestanding silicon nitride membrane perforated with hexagonal air holesarray were fabricated with various lattice constants and hole diameters. The keyfabrication techniques were including photolithography, KOH wet etching, electronbeam lithography, and reactive ion beam etching. As a converged light impinges onthe slab normally, the guided resonances are evidenced through the transmissionspectra, in which the resonant wavelengths appear in corresponding to the latticeconstant of the PCS. Moreover, the absorption dips are split and shifted to shorterwavelength by increasing the hole diameters of the PCS. The band structures of PCScalculated by using the plane wave expansion method reveal that the positions ofguided resonance and mode splitting behavior are agree well with the experimentaldata.

References

1. K. B. Crozier, Virginie Lousse, Onur Kilic, Sora Kim, Shanhui Fan, and Olav Solgaard, Phys. Rev. B

73, 115126 (2006).

2. S. H. Fan and J. D. Joannopoulos, Phys. Rev. B 65, 235112 (2002).

3. McPhedran, D. J. Moss, M. J. Steel, and B. J. Eggleton, Opt. Express 14, 369–376 (2006).

4. W. Suh, O. Solgaard, and S. Fan, J. Appl. Phys. 98, 033102 (2005).


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A4Distribution of Germanium in SiO2/Ge/Si structure by using scanning near-field

optical microscopyJing-Jie. Tao, Jia-Tsung Juang, and Yun-Wu Suen

Department of Physics, National Chung Hsing University, Taichung, Taiwan

Abstract

We reported the detection of the spatial distribution of Germanium film depositedon a patterned Si substrate with a SiO2 cap by using scanning near-field opticalmicroscopy (SNOM) with an infrared laser source. The pattern on Si substrate is ahole array consisted of every hole with 200 nm diameter, 20 nm depth, and 800 or1000 nm interval. In this report, the SNOM technique has been achieved analternative nondestructive testing and certification to identify the distribution ofmaterial covered by a thin film.


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A5Electron Beam Induced Deposition for Tip Apex Modification

Y.-H. Ku,1 and M.-N. Chang,1

P.-L. Chen,2 C.-C. Yang,2 and C.-Y. Su2

1Department of Physics, National Chung Hsing University, Taichung, Taiwan2Instrument Technology Research Center, National Applied Research Laboratories, Hsinchu, Taiwan

Abstract

In this work, we have modified conductive tips by electron beam induced deposition (EBID) in

order to improve the measurements of electrical scanning probe microscopy (E-SPM). For a conductive

tip apex, we employed a focused ion beam (FIB) system to deposit a platinum nano-rod at the tip apex.

Figure 1 shows the tip apex before and after platinum modification. The samples used in this study are

surface quantum rings and quantum dots on semiconductor substrates. Experimental results indicated

that the modified conductive tips can be used to improve the image quality of scanning Kelvin probe

microscopy (SKPM) and electrostatic force microscopy (EFM).

Fig. 1. Tip apex before (left) and after (right) modification.


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B1Direct current effect on the Microstructured spin valves ellipses

C. Y. Kuo (郭政宜)1, C. T. Chao(趙建都)1, Lance Horng (洪連輝) 1, M. Tsunoda2, M. Takahashi2, and J.

C. Wu (吳仲卿) 1

1 National Changhua University of Education (Department of Physics, Changhua, Taiwan)2 Tohoku University (Department of Electronic Engineering, , Aobayama 05, Sendai, Japan)

Abstract

A series of differential magnetoristance curves were measured to investigate the joule heating and

magnetization reversal behaviors of spin valve devices. The elliptical spin-valve patterns, having

current-in-plane configuration, with nonmagnetic current/voltage leads were defined by using E-beam

lithography and then transferred into stack film of spin valve by ion beam etching. The spin valve

devices were electrically characterized using differential magnetoresistance measurements and

low-field ac measurements at various ambient temperatures. The differential magnetoresistance

measurements were carried out with various direct currents which were superimposed with a low

sensing ac current. Generally, the direct current will induce a Joule heating effect and an Oersted field

is generated. Joule heating effect due to direct current injection was identified through a temperature

dependent magnetoristance measurement. The relationship between direct current and temperature

effects can be correlated through R-T and R-I2 curves. Since the directions of hard layer pinning and

direct current were aligned in the long axis of the elliptical device, an Oersted field was generated in

the short axis of device and thus affects the switching properties. Consequently, the coercive field

reduces with increasing direct current. Furthermore, the current scanned data taken under different

fixed external field illustrate that the magnetization of free layer can be reversed by direct current and

the reversal behavior is dependent on the current direction. This indicates that in addition to the Oersted

field, another influence may be accounted on the direct current. In order to analyze the switching

properties by correlating the current scanned and the field scanned minor loops, a spin transfer torque

in the spin valve devices should be addressed.


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B2

Study of magnetization configuration and switching behavior in submicro-scaled

asymmetric Permalloy ring

Nian-jia Cheng(鄭念佳), Chao-Hsien Huang(黃昭憲), Cheng-Ta Yang(楊政達), J.C.Wu(吳仲卿),

Lance Horng(洪連輝)

Department of physics and Taiwan SPIN Research Center, National Changhua University of Education,

Changhua 500, Taiwan

We have simulated magnetization configuration and switching behavior with thein-plane magnetic field in asymmetric permalloy ring. By introducting a inner hole asan ellipse or circle,and its center is shifted along the diameter, we can achieve theflux-closure chirality control, either clockwise or counterclockwise, and two typesasymmetric ring have opposite chirality with same in-plane magnetic field.Micromagnetic simulation work was performed using the object orientedmicromagnetic framework (OOMMF) on asymmetric permalloy ring to observe itsmagnetic switching behavior. The asymmetric ring structure facilitates the applicationof the ring dots to magnetic random access memories.


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B3Structure and magnetic properties of pulse-laser-deposited FePt films

C. W. Yuan (袁志瑋)1, C.W. Shih (石至為)2, H. W. Chang (張晃暐)3, and C.R. Wang(王昌仁)4

1 Department of Physics, Tunghai University, Taichung, Taiwan.2 Department of Physics, National Chung Cheng University, Chia-Yi, Taiwan.

Abstract

Due to high anisotropy constant (Ku = 7× 107 erg/cm3), coercivity (Hc), thermal stability

(Tc = 450 ℃), and also good corrosion resistance, FePt alloy with Face-Center-Tetragonal (FCT)

structure is promising as a next generation high-density magnetic recording media and a permanent

magnetic material. [1-4] Over the decades, magnetic properties and disorder-ordering transformation in

the FePt alloys were widely studied. [2-3] In recent years, much attention has focused on the FePt

alloys in thin film form, and the main method to fabricate FePt thin films is magnetron sputtering

technique.[4] However, very limited papers report on the study of FePt thin films, fabricated by pulse

laser deposition (PLD). Therefore, we adopted pulse laser deposition (PLD) to fabricate FePt thin films

on Corning glass substrates at ambient temperature following post-annealing using rapid thermal

annealing (RTA) and studied their structure and magnetic properties. First, influence of two kinds of

the laser wavelength (λ) employed to deposit FePt thin films on their structure and magnetic properties

have been compared. For thermal evaporation-like PLD, the longer wavelength of 532 nm used to

deposit FePt films, the composition of the resultant films deviate from the equal atomic ratio of Fe-Pt

and form the Pt-rich FePt film, leading to make the FePt films more difficult to reach ordering state and

poor permanent magnetic properties. On the other hand, for ablation deposition-like PLD, the shorter

laser wavelength of 266 nm adopted to deposit FePt films, the FePt film can retain the composition of

original target, making it easier to form the L10-FePt phase. In addition, introducing applied magnetic

field, produced by NdFeB magnet placed under the glass substrate, of 3.6 kOe and perpendicular to the

film surface is helpful in improving the composition deviation for λ = 532 nm and also the squareness

of demagnetization curve (SQ) forλ = 266 nm, respectively.

References

1. K. Watanabe et al. , IEEE Trans. Magn. 23, 3196 (1987).

2. S. C. Chen et al. , J. Appl. Phys. 97, 10N107 (2005).

3. Z. L. Zhao et al. , Appl. Phys. Lett. 88, 052503 (2006).

4. M. Weisheit et al. , J. Magn. Magn. Mat. 290, 570 (2005).


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B4Size-induced valence transition in Ce3Pt4 and CeAuAl3 alloysD.Y Tsai(蔡德穎),J.S Yeh(葉日旭), Y. L. Chan(詹育霖),C.R Wang(王昌仁)

Department of physics, Tunghai University, Taichung, Taiwan, R.O.C.

Abstrac

Both Ce3Pt4 and CeAuAl3 compounds in bulk form belong to antiferromagnetism, and the Neel

temperature (TN) are 2.8 K for the former and 1.32 K for the latter, respectively. To understand the

magnetic and thermal characterization of these alloys in small sizes, the nanoparticles of Ce3Pt4 and

CeAuAl3 nanoparticles were fabricated by pulsed laser deposition (PLD). The x-ray diffraction (XRD)

shows that Ce3Pt4 and CeAuAl3 alloys mainly consist of pure Ce3Pt4 with rhombohedral Pu3Pd4

structure and pure CeAuAl3 with tetragonal BaNiSn3 structures , respectively. The transmission

electron microscopy (TEM) analysis displays that their average particle sizes were about between 1.5 ~

4.5 nm. Based on the magnetic measurements, no antiferromagnetic order is found for temperature

above 2K on χ-T curve, and the Curie constants, obtained by fitting χ-T curve, for the Ce3Pt4 (0.06

emu/mole*K) and CeAuAl3 (0.134 emu/mole*K) nanoparticles are much smaller than those for the

Ce3Pt4 (0.63 emu/mole*K) and CeAuAl3 (0.754 emu/mole*K) bulks, respectively. The small Curie

constant reveals an occurrence of the valence transition from Ce3+ to Ce4+. This behavior is the same

with that of Ce-Al compound in previous study[1]. Moreover, the specific-heat measurement also

gives more an evidence to the valence transition behavior and reveals a competition between RKKY

interaction and Kondo effect for these Ce-based nanoparticles.

References

Y. Y. Chen , Y. D. Yao , T. K. Lee , C. R. Wang , S. F. Pan , W. H. Li and C. L. Chang ,Size-Induced

Transition from Magnetic Ordering to Kondo Behavior in (Ce,Al) Compounds, Phys. Rev. Lett. Vol.84

p4990 (2000)


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B5Design and Test of a Measurement System using Planar Gradiometers and

Superconducting Quantum Interference Device蘇于宗中興大學物理

We present a measurement system incorporating a superconducting quantuminterference device (SQUID) and planar gradiometers for detecting smallmagnetization signals from the sample placing at low temperature (down to 1.5 K)and in high magnetic field (up to 14 T). The SQUID is from STAR Cryoelectronics.We have designed and fabricated a planar gradiometer to cancel the backgroundmagnetic field and noise. We measured the variation of the magnetic dipoles of aGaAs chip at 1.5 K in strong magnetic fields. However, the observed variation of themagnetic moment is different from what is expected theoretically. We providesuggest ions to improve the measurement system for better resul ts .


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C1

Graphene Edges Identified by Polarization-Dependent RamanSpectroscopy

Y.-H. Li1, A. C.-E. Cheng1,2, C.-S. Chang2, and F. S.-S. Chien1

1Department of Physics, Tunghai University, Taichung, Taiwan

2Department of Photonics, National Chiao Tung University, Hsinchu, Taiwan

The edges of single-layer grapehens were identified with a 90° corner in this study.

The Raman intensity of D-band was maximum as the polarization (P) of incident laser

was parallel to edge and minimum as perpendicular, due to the intensity of D-band is

proportional to P×D, where D is the electron back-scattered wavevector. The

normalized intensity of D-band at armchair edge is stronger than zigzag edge was

observed. The armchair and zigzag edges of graphene was identified by studying the

angle-dependent Raman spectrum of single layer graphene.

REFERENCES

[1] A. Reina, X. Jia, J. Ho, D. Nezich, H. Son, V. Bulovic, M. S. Dresselhaus, and J. Kong, Large

Area, Few-Layer Graphene Films on Arbitrary substrates by Chemical Vapor Deposition, Nano

Lett. 9, 30 (2009).

[2] Y. Meng You, Z. H. Ni, T. Yu, and Z. X. Shen, Edge chirality determination of graphene by

Raman spectroscopy, Appl. Phys. Lett. 93, 163112 (2008).

[3] C. Casiraghi, A. Hartschuh, H. Qian, S. Piscanec, C. Georgi,A. Fasoli, K. S. Novoselove, D. M.

Basko, and A. C. Ferrari, Raman Spectroscopy of Graphene Edges, Nano Lett. 9, 1433 (2009).

[4] J. Moser, A. Verdaguer, D. Jimennez, A. Barreiro, and A. Bachtold, The environment of graphene

probed by electrostatic force microscopy, Appl. Phys. Lett. 92, 123507 (2008).


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C2Characteristics of carbon nanotube and ZnO nanorod field effect transistors

Y.-C. Lin(林宥辰), T.-T. Tsai(蔡宗唐), C.-C Su(蘇志川),M.-S. Ho(何孟書)

Department of Physics, National Chung Hsing University, Taichung 402, Taiwan

Abstract

In this study, we fabricated the multi-wall carbon nanotube (MWCNT) and ZnOnanorodsbased field

effect transistors(FETs) by electron beam lithography. The ZnOnanorods were first growthed by

vapor-liquid-solid(VLS) method, and then examed by scanning electron microscope, transmission

electron microscope, X-Ray Diffraction andEnergy dispersive spectrometer to determine the

composition is zinc oxide and the growing direction is (002).

The MWCNT FETswere verifiedas P-type FETs. The electrical properties of multi-wall carbon

nanotubes wasmeasured.The results shown that the current is exponential growing with voltage. We

speculate that the junction of gold and carbon nanotubes is Schottky contact. The diode like behavior of

MWCNT FETs shown that the nature of multi-wall carbon nanotubes is semiconductor. Moreover, the

diode reverse saturation current was measured around 0.5nA.


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C3Field Emission Characteristic of C84 imbedded Silicon Surface Using Scanning

Tunneling MicroscopyF. Y. Chiu(邱凡芸),1 C. P. Huang(黃至鵬),1 W. S. Su(蘇萬生),2 C. C. Su(蘇志川),1 C.

F. Hsu(徐巧芳)1 and M. S. Ho(何孟書)1

1Department of Physics, National Chung Hsing University, Taichung 402, Taiwan2National Center for High-Performance Computing, Tainan 741, Taiwan

AbstractC84 is fullerene molecule with elliptical shape. According to previous studies, the

self-assembly C84 overlayer embedded Si surface has excellent field emissioncharacteristic. In this experiment, ultrahigh-vacuum scanning tunneling microscopywas used to observe the topography of C84 embedded in Si(111) surface, and scanningtunneling spectroscopy (STS) was used to measure the electronic characteristic. Tocompare the results of different adsorption, single C84 molecule, C84 monolayer andbare Si(111) subtract was measured and obtained I-V curve, band gap, field emissioninformation. The experiment showed that the band gap energy of single C84 moleculeis similar to Si substrate but C84 monolayer presented a nearly twice wider band gap.In the case of field emission characteristic, the single C84 molecular showed muchgreater field enhancement factor β than the monolayer C84 molecule, results as aninfluence of screen effect. In conclusions, change the distance between fullerenemolecules can affect the field enhancement factor of sample. These properties of theC84 imbedded surface can widely apply in nanotechnology.


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C4Ion conduction through nanopores on silicon nitride membrane

Wun-Fong Wang,1 and Watson Kuo1

1Department of Physics, National Chung Hsing University,Taichung 402, Taiwan, ROC

Abstract

In this study, we built a ion conductance monitoring system based on single solid-state nanopore.

Standard semiconductor manufacturing technology were applied for fabricating single nanometre-sized

pore on silicon nitride membranes suspending on silicon chips. The chip surface was first modified

hydrophilic using air-plasma treatment to assist the bonding with polydimethylsiloxane (PDMS) fluidic

reservoir. Then 1M KCl solution was injected into the PDMS reservoir by using gravity-induced

pressure difference. By placing electrodes on both sides of the chip, we conducted the four-probe

measurement on the ion conduction through the nanopore.

This ion conductance monitoring system may lead to several interesting applications. Firstly, we

may use Langmuir-Blodgett deposition method to transfer the dipalmitoylphosphatidylcholine(DPPC)

lipid bi-layers upon the solid-state nanopore. Secondly, we may stuck a biological cell in the nanopore

to form a gigaseal in a typical patch-clamp experiment. With this structure, we may study the

electroporation property of the artifical and real bio-membranes, and further study membrane proteins

and biological ion channels. We may also combine the atomic force microsopy(AFM) in this ion

conduction monitoring system by using a conductive AMF probe. By doing so, one may scan the cell’s

surface morphology as well as map ion-conduction simultaneously .

Documents

Tunghai University Low Dimensional Science Workshop 2010 Fallezphysics.nchu.edu.tw/LDS/workshop/2010fallworkshop/LDS_information.pdf · LDS Workshop, 2010 Fall Tunghai University