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Introduction to Nanophysics

Introduction to Nanophysics 2
Introduction to Nanophysics Prof. J. Raynien Kwo Department of Physics National Tsing Hua University Feb. 21, 2013 What is the size for a “nano” ? -9 One (nm) equals to 1/1000000000 (10 ) meter -3 10 m , Macro -6 10 m , Micro -9 10 m , Meso 1 R. Feymann Already Knew about this “ There’s plenty of room at the bottom ” in 1959. 2 Physicists noticed the “Nano ” as early as ….. • 4th Century, Roman glassmaker: the color of glasses can be changed by mixing in metal particles • In 1883, Films containing silver halides for photography were invented by George Eastman, founder of Koda.k • 1908, Gustay Mie first provided the explanation of the size dependence of color. • Vision from Feynman in 1959: “There is plenty room at the bottom”, and also recognized there are plenty of nature-given nanostructures in biological systems. • 1950-1960, small metal particles were investigated by physicists. • 1957, Ralph Landauer realized the importance of quantum mechanics plays in devices with small scales. • Before 1997 = mesoscopic (or low dimensional) physics : quantum dots, wells, wires…..are known already. 3 Major Topics of Nanoscience and Technology Nano Materials Nano Science and Technology Nanoproducts Nano Processing (Devices and and Systems) Characterization 4 What is the Nano Technology?  Science and Technology Down scaling to size under100 nm: Via the “Top-down” lithographic pattering. Moore’s law  Manipulate the atomic and molecular structures:“Bottom-up” nano materials, growth and assembly. Feymann: There’s plenty of room at the bottom 5 Major Driving Force pushing for Nano Is due to the bottle neck met in Microelectronics Moore‘s Law : A 30% decrease in the size of printed dimensions every two years. 6 Metal-Oxide-Feld Effect Transistor 1960 Kahng and Atalla, First MOSFET 1970 First IC, 1 kbit, 750 khz microprocessor 8 Bottom-up Nano systems & Self-Assembly enabling of designing large molecules and nano materials 11 The First Lesson : Bulk-to-nano Transition 12 Ex: size-dependence of melting temperature Ag Ph. Buffat and J-P. Borel, Phys. Rev. A13, 2287 (1976) 13 Ex: size-dependence of color powered cadmium selenide larger smaller 14 Ex: size-dependence of magnetism A. J. Cox et al. Phys. Rev. B49, 12295 (1994) 15 The Second Lesson : • The ability of growing the nano scale materials and structures • The ability of detecting and manipulating on the nano scale. 16 (I) Advance in thin film growth: Such as Molecular Beam Epitaxy, atomic layer depostion, laser MBE, etc…  For Nano electronics in metals, oxides, and semiconductors (II) Detection at nano scale : STM, AFM, MFM, STEM, Cs-TEM  In 1982, Binning, and Rohrer in IBM invented scanning tunneling microscope.  In 1986, Binning, Quate, and Gerber invented the atomic force microscope AFM. 17 Integrated MBE Multi-chamber System Now located in the Nano Technology Center, ITRI, Hsin Chu, Taiwan For Metal, Oxide and Semiconductor Films On the Nano scale 18 Scanning Tunneling Microscope (STM) 19 Quantum Corral of 7.13 nm radius, 48 Fe atoms Fe Crommue, Luts, and Eigler, Science 262, 218-220, 1993 20 Scanning Transmission Electron Microscope Laboratory 2-Å STEM 1-Å STEM E0.2 eV E0.9 eV Prof. C. H. Chen and Dr. M.-W. Chu. Electron Mono- chromator EDX C s corrector EELS EELS Spherical Aberration Corrected (球面相差) Cs-STEM by C. H. Chen at CCMS, NTU Cs sample lens Cs corrector focus confusion Cs corrected sample lens JEOL 2100; 2009四月底 Cs 裝機完成 corrector High-Angle ADF: Si dumbbell, 1.36 Å spacing 15s exposure 60s exposure (440); Si 110 0.96Å Drift 1Å /min (004): 1.36Å InAlAs InGaAs InGaAs InAlAs InGaAs InP-substrate InGaAs/InAlAs superlattices on InP Substrate InGaAs InP • Determining the interface location and sharpness is easy. • The In-distribution seems to be inhomogeneous in the InAlAs layer (blue arrows). • Note that InP substrate is In- terminated (red arrow). Atomic Resolution STEM Imaging: Z-contrast 2-Å Electron Probe SrTiO 3 Z-contrast Sr Ti O cubic; a = 3.905 Å Electronic Exc.: Electron Energy-Loss Spectroscopy (EELS) E ,k i i Coulomb Interaction 2 sample e vr ()   rr  j j E ,k iqr f f  ve   qq E ,k i i q E  E E if E, q  , where the electron density operator q q k k if Inelastic Scattering (∆E) Probability 2 2 d   v(q)    (E E  E)  f i i f dd E f 1 Sq (, ) X-ray 4 q  11 Im EELS 2  qq  ( , ) Spectral Imaging at Ultimate Spatial Resolution Plasmonic Mapping: Chemical Mapping: STEM-EELS (2-Å Probe) STEM-EDX (1-Å Probe) 27 nm 8 nm Au Au 81 nm 1.82 eV Dark Mode Bright Mode 2.38 eV 1.47 Å M.-W. Chu et al., Nano Lett. 9, 399 (2009). M.-W. Chu et al., Phys. Rev. Lett. 104, 196101 (2010). The Third Lesson: The importance of Quantum Physics 28 The cause for variation of scaling • Influence of Boundary Increase of proportion of boundaries Existence of surface / edge modes Geometrical reconstruction • Decrease of the number of particles decrease of confinement , increase of purturbation • Different scaling for different physical entity Quantum Effect: = Most likely to have new breakthough 29 The connection of materials wave with mechanics h = Planck constant -34 (6.62610 joule-sec) DeBroglie: Einstein: 2  = h/p E=h=p /2m  自由電子:  (300K)  6.2nm Free electrons Wave length th Semiconductors ( 半導體中) 10nm    100nm 原子:  (300K)  0.2nm Atoms thNano Limit Bulk Limit Bulk materials L  L Nano  L 31 Major Qauntum Effect at the nano scale • Interference • Quantization • Tunneling • Quantum Spin 32 (I) Interference 33 The wonder of electron in waves Classical mechanics Electron source  ? 34 The wave property of electrons  35 Double Slit Interference of Electrons Electron source 36 L L  y   d d dsin = m constructive interference y d   dsin = (m+1/2) L distructive interference 37 Lm 1 L  y  d  14 d 10 mm 10 m  700nm  7mm  0.17nm  y 1.7m 38 (II) Quantization 39 Confinement of the materials wave Standing Wave Quantizations 40 The Qauntization of Energy n n3  L   2 h nh n2  p  2L 2 EL 1/ 22 2 p n h E n1  n 2 28 m mL 41 L Quantum well: 1D confinement AlGaAs 2D electron Gas MOSFET: GaAs 二維電子氣 e E F AlGaAs GaAs 42 Quantum wire: 2 D-Confinement x z y SEM images of MoO nanowires on graphite surfaces x Science 290, 2120-2123, (2000) 43 Quantum dot: 3 D - Confinement 44 Quantum Dots of various shape 45 Absorption in scattering From red to yellow 2  E hc /  1/L  larger 0 powdered Cadmium Selenide larger smaller 46 The Advent of Carbon Era ? Carbon Nanotube 50 Carbon Nanotube Carbon Nanotube based Transistors / Electronics 51 Exfoliated Graphene Monolayers and Bilayers Reflecting microscope images. 20 m Monolayer Bilayer K. S. Novoselov et al., Science 306, 666 (2004). Band Structure near K Points 10 eV Relativistic Dirac fermion. General Properties of Graphene Electrically: High mobility at room temperature, Large current carrying capability Mechanically: Large Young’s modulus. Thermally: High thermal conductance. Exotic Behaviors -Quantum Hall effect -Barry Phase -Ballistic transport -Klein’s paradox -Others . . Quantum Hall Effect Y. Zhang et al, Nature 438, 201(2005) Electron scattering from a potential barrier (1929) As the potential approaches infinity, the reflection diminishes, the electron always transmittes Another emerging wonder material : Silicene • Graphene-like two-dimensional silicon • Could be more compatible with existing silicon-based electronics • Potential application as a high-performance field effect transistor Nature, Scientific Reports 2, 853, 2012 Superconductivity in alkaline or To grow Silicene, Germanine, and alkaline earth elements doped even Tinene on insulating or silicene (CaC T =13K; CaSi T = ? ) semiconducting substrate. 6 c 6 cCombined spectroscopic and microscopic study underway Synchrotron radiation core level Scanning Tunneling Microscopy photoemission from NSRRC 60s = 1 ML (III) Tunneling 67 nm 68 Quantum Tunneling is the major effect for the failure of Transistor at nano scale 69 Scanning Tunneling Microscope (STM) – Physicist used to detect the nano structures Nature 409, 304(2001) 70 Doping-structure correlation at fullerene/metal interface (interface engineering) C /Cu(111) case: 60 - “optimal” doping (e.g., 3 e per C ) achieved purely through interface reconstruction. 60 Combined techniques of STS, STM, PES, LEED I-V, and ab-initio theory are used in this study. Reality… Naï ve case structure-doping correlation thought to be true Implication: electronic property of molecule-electrode contact must consider structural details at the interface W. W. Pai et al., Phys. Rev. Lett. 104, 036103 (2010) (IV) Quantum Spin 72 Spin and Nano technology Electron Spin is the smallest unit of magetism, Came from Quantum Mechanics N  S 73 Often being used for magnetic recording 30 billion market Spintronics  Electronics 74 New generation of computer Compulttion and storage in one shot When turn-on, it is ready 75 Quantum behavior of ferromagnets -Spin as a quantum qubit z /2 qubit  0  1 1  Due to superposition More information 0   /2 76 Can we take the “charge” out of Spintronics ? To generate pure spin current Courtesy Claude Chappert, Université Paris Su, INTERMAG 2008, Madrid, Spain Spintronics vs Electronics Reducing the heat generated in traditional electronics is a major driving force for developing spintronics. Spin-based transistors do not strictly rely on the raising or lowering of electrostatic barriers, hence it may overcome scaling limits in charge-based transistors. Spin transport in semiconductors may lead to dissipationless transfer of information by pure spin currents. Allow computer speed and power consumption to move beyond limitations of current technologies. 78 Reliable generation of pure spin currents  Spin Hall effect (2004)  Spin Pumping (2006)  Inverse Spin Hall effect (2006)  Spin Seebeck effect (2008)  Spin Caloritronics (2010) 79 Major Qauntum Effect at the nano scale • Interference • Quantization • Tunneling • Quantum Spin 80 The Fourth Lesson: Innovations of nano structures and nano materials for various applications Overview of Advanced Materials Laboratory Pt-Ru NP on CN NT Ag NP on Si NT x GaN Nanobridge Au NP SiO NW x 100 nm SERS: Fuel Cells, Molecule/Bio-sensing Color-selective Optical Supercapacitors High-gain Photo-detector, Switch, SPR-enhanced Solar Cells, Bio-sensor Sensor Li-Chyong Chen Center for Condensed Matter Sciences National Taiwan University The Nano-world at CCMS-AML: a Fruitful Research Field with Technology Implications JACS 123, 2791 (2001) APL 83, 1420 (2003) APL 81, 22 (2002) Nano. Lett. 4, 471 (2004) JACS 127, 2820 (2005) Chem. Mater. 17, 553 (2005) APL 88, 241905 (2006) Wire/Rod Adv. Func. Mater. 15, 783 (2005) APL 90, 213104 (2007) APL 86, 203119 (2005) Adv. Func. Mater. 18, 938 (2008) US Patent 6,960,528,B2 Nanotip Small 4, 925 (2008) APL 89, 143105 (2006) Analytical Chem. 81, 36 (2009) Nature Nanotech. 2, 170 (2007) Nano Lett. 9, 1839 (2009 APL 79, 3179 (2001) APL 81, 4189 (2002) Adv. Func. Mater. 12, 687 (2002) Tube APL 86, 203119 (2005) Chem. Mater. 17, 3749 (2005) JACS 128, 8368 (2006) APL 81, 1312 (2002) Core-shell PRB 75, 195429 (2007) Nano. Lett. 3, 537 (2003) JACS 130, 3543 (2008) Chapter 9, pp. 259-309, Adv. Func. Mater. 14, 233 (2004) Nanowires and nanobelts, Z.L. Wang Ed., Kluwer (2004) Adv. Func. Mater. 16, 537 (2006) APL 90, 123109 (2007) Belt Other Thin Films: Adv. Mater. 19, 4524 (2007) APL 86, 21911 (2005) APL 86, 83104 (2005) APL 86, 161901 (2005) APL 87, 261915 (2005) Adv. Mater. 14, 1847 (2002) JVST B 24, 87 (2006) Brush Peapod Nature Mater. 5, 102 (2006) APL 88, 73515 (2006) Adv. Mater. 21, 759 (2009) Si Nanotips-Array and their Hetero-junctions: On-chip, IC-compatible Antireflection: o Broadband (uv-terahertz), Omnidirectional (70 ) Electroluminescence in ZnO/SiNTs: IR emission, x10 higher; turn-on 3V, x2 lower than film Magneto-resistance in LSMO/SiNTs: p-CMR Room-temp. MR at lower bias and magnetic field n-Si H ZnO/SiNT IR-LED Nature-Nanotechnology Nano Letters Promising high-density memory: 2 (2007) 770 9 (2009) 1839 On-going A Man-made Moth Eye Broadband and Quasi-omni-directional Anti-reflection Properties with Biomimetic Silicon Nanostructure Y. F. Huang, et al., Nature Nanotechnology 2, 770-774 (2007) & US Patent 2005 Featured by NPG Asia Materials, March 2008 - -1 1 Waven Wavenumb umber er ( (cm cm ) ) UV- UV-VIS- VIS- NI NIR R 4000 4000 3000 3000 2000 2000 1000 1000 500 500 100 100 100 100 S Sii-W -Waf afer- er-N+ N+ S Si i sub substrat strate e E ECR CR 83 833-SiN 3-SiNT Ts s -N+-R% -N+-R% 80 80 Si Si s substr ubstrate ate Mid - Mid - IR IR E ECR CR 85 852 S 2 SiiNT NTs-N+ s-N+ S SiN iNT Ts , s , L L= = 1 1.6 .6  m m 80 80 E ECR CR 83 835-SiN 5-SiNT Ts-N+ s-N+ Si SiNT NTs s , L= 1.6 , L= 1.6  m m 60 60 S SiN iNT Ts , s , L L= = 5 5.5 .5  m m Si SiNT NTs s , L= 5.5 , L= 5.5  m m S SiN iNT Ts , s , L L= = 1 16 6.0 .0  m m 40 40 60 60 Si SiNT NTs s , L= 16 , L= 16  m m 10 10 40 40 1 1 20 20 0 0 0.1 0.1 2.5 2.5 20 20 0.2 0.2 0.5 0.5 1.0 1.0 1.5 1.5 2.0 2.0 2.5 2.5 5 5 10 10 15 15 Wavelengt Wavelength h ( (μ μ m m) ) Wavelengt Wavelengt h h ( (μ μ m m) ) X Ax X Axiis T s Tiittlle e Wa Wave vele leng ngth th ( (  m m) ) Many plants and animals have tiny surface structures that absorb certain wavelengths of light. These naturally formed nanostructures provide the colors in butterfly wings, camouflage for cicadas and enable moths to capture as much light as possible when flying at night. Now, we have created nanostructure surfaces which mimic moth eye and surpass its function in anti-reflection in that they absorb almost all incident light. R Re ef flle ec ct ta an nc ce e ( (% %) ) Re Reflect flectan ance ce ( (%) %) Y Y Ax Axiis T s Tiittlle e Re Reflect flectan ance ce ( (%) %) Building a Nano-scale Bridge On-chip On-chip Fabrication of Well Aligned and Contact Barrier-Free GaN Nanobridge Devices with Ultrahigh Photocurrent Responsivity R. S. Chen, et al., Small 4, 925-929 (2008) GaN nano-bridge h wafer process W probe + - he Ni GaN NW doped GaN 5μm c-plane Sapphire • Nanowire: Naturally formed core-shell structure, 1D electron gas-like property • On-chip process for building GaN nanobridge devices, which provide a large surface area, short transport path, and high responsivity for next-generation sensors and detectors A Color-selective Nanoswitch Photosensitive Gold Nanoparticle-embedded Dielectric Nanowires M. S. Hu, et al., Nature Materials 5, 102-106 (2006) A Fast Breaking Paper (in each individual field, only 1 was selected bimonthly among the Highly Cited Papers) (http://esi-topics.com/fbp/2007/august07-Li-ChyongChen.html) In ancient Arabian story of “Ali Baba and the Forty Thieves”, the treasure is in a cave, of which the mouth is sealed by magic. It opens on the words "Open Sesame" and seals itself on the words "Close Sesame". The nanopeapod (i.e., gold nanoparticle-embedded dielectric nanowire) will open to green light but shut for lights of other colors. Next-generation Energy Solution (I): Fuel Cell with Low-loading of Precious Metals Ultrafine Pt Nanoparticles Uniformly Dispersed on Arrayed Carbon Nanotubes with High Electrochemical Activity at Low Loading of Precious Metal C. L. Sun, et al., Chemistry of Materials 17, 3749-3753 (2005) C. H. Wang, et al., J. Power Sources 171, 55-62 (2007) 20 100 0.4 mg/cm2 Pt-Ru/CNT-carbon cloth 15 2 nm 3.0 mg/cm2 60% Pt-Ru/C (ETEK) 10 4.0 mg/cm2 30% Pt-Ru/C (Home made) 80 5 4.0 mg/cm2 20% Pt-Ru/CNT (Home made) 0 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 Diameter(nm) 60 40 20 0 0 100 200 300 400 500 600 2 j / mA/cm • Direct methanol fuel cell is promising power generator with a wide range of applications from portable electronic devices to automobiles. • Nanotubes-Pt/Ru composites are highly efficient in loading precious metals. Only one tenth of metal loading, in comparison to the conventional, is needed. Number 2 P / mW/cm Next-generation Energy Solution (II): High-performance Supercapacitor Ultrafast Charging-discharging Capacitive Property of RuO Nanoparticles on 2 Carbon Nanotubes Using Nitrogen Incorporation W. C. Fang, et al., Electrochemistry Communications 9, 239-244 (2007) W. C. Fang, et al., J. Electrochemical Society 155, K15-K18 (2008) 1.50 70 2 I = 23 mA/cm Nanocomposites Scan rate = 600 mV/s Scan rate = 600 mV/s RuO films 2 0.75 0 CN NTs x RuO films 2 0.00 CN NTs-RuO x 2 -70 0 5 10 15 20 0.0 0.2 0.4 0.6 0.8 1.0 Time (s) E (V vs. Ag/AgCl) RuO on N-doped 2 CNT composites • 4 fold increase in capacitance (BEI) • Optimal capacitance of 1380 F/g at 600 mV/s (theory: 1450 F/g) 2 • Output current as high as 23 mA/cm (SEI) • Stable at high scan rate • 10 fold increase in charge-discharge rate 2 Capacitance (mF/cm ) Potential (V vs. Ag/AgCl) The Fifth Lesson: Nano photonics and Bio-applications Nano-photonics and Plasmonics Near-field examination of blue-ray discs Dr. Juen-Kai Wang, CCMS, NTU S-SNOM setup Scattering-type SNOM reveals sub-10 nm optical signature. The optical contrasts of the dark and the bright regions in near-field image of phase- change layer correspond to amorphous and polycrystalline AgInSbTe, respectively. Small bright spots with a size of 30 nm emerge within the dark region, corresponding to the nano-sized ordered domains in the TEM image. s-SNOM provides a direct optical probe in nanometer scale for high density optical storage media. J. Y. Chu et al., Appl. Phys. Lett. 95, 103105 (2009). Creating Monodispersed Ordered Arrays of Surface-Magic-Clusters and Anodic Alumia Nanochannels by Constrained Self-organization Dr. Juen-Kai Wang, CCMS, NTU Prof. Yuh-Lin Wang 王玉麟 IAMS Academia Sinica, Taiwan A High Sensitivity and High Speed Biomedical Diagnostic Technology using SERS Dr. Juen-Kai Wang, CCMS, NTU Prof. Yuh-Lin Wang 王玉麟 93 IAMS Academia Sinica, Taiwan SERS detection of bacterial cell wall Dr. Juen-Kai Wang, CCMS, NTU Sensitive and stable SERS profiles based on our substrates readily reflect different bacterial cell walls found in Gram-positive, Gram-negative, and mycobacteria group. Characteristic changes in SERS profile are recognized in the drug-sensitive bacteria of antibiotic exposure, which could be used to differentiate them from the drug-resistant ones. H.-H. Wang et al., Adv. Mater. 18, 491 (2006); T.-T. Liu et al., PLoS ONE 4, e5470 (2009). The End
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