Nanomaterials Electrical and Optical Properties

Size: px
Start display at page:

Download "Nanomaterials Electrical and Optical Properties"

Transcription

1 Nanomaterials Electrical and Optical Properties H.Hofmann

2 ÉCOLE POLYTECHNIQUE FÉDÉRALE DE LAUSANNE Electrical Properties Energy LUMO HOMO Forbidden bandgap Atom Mo lecule Cluster Nanoparticle Semi conductor Crystalline Metal

3 Quantized Energy Levels The narrower the space, the smaller the crystal the larger the frequency & energy gap between those modes More confined spaces have wider energy gaps between their distinct momentum states. λ/3, 3E λ/2, 2E λ, E

4 Electrical conductivity in metallic nanostructures Some theoretical aspects Metallic nanowire

5 F the Fermi wavelength; wavelength of carriers that dominate electrical transport. In semiconductors, may be as long as 100 nm, while in traditional metals is more like 0.1 nm web.edu.ioffe.ru/register/galperin/qlu1_9.eps.png

6 Ballistic Transport Quantized conductance results from the electronic wave guide properties of extremely fine wires and constrictions. When the length of the conductor is smaller than the electronic mean free path, then the electronic transport is ballistic, in which case each transverse wave guide mode or conducting channel contributes σ 0 to the total conductance. Calculations indicate that conducting single-shell nanotubes have two conductance channels. This predicts that the conductance of a single-wall nanotube (SWNT) is 2G 0 independent of diameter and length. Another important aspect of ballistic transport is that no energy is dissipated in the conductor. Instead, the Joule heat is dissipated in the electrical leads, which connect the ballistic conductor to the macroscopic elements of the circuit. The nondissipative property survives if elastic scattering occurs, for example, from impurities and defects. However, elastic scattering affects the transmission coefficients and thereby reduces the conductance, which then is no longer precisely quantized. Carbon Nanotube Quantum Resistors Stefan Frank, Philippe Poncharal, Z. L. Wang, Walt A. de Heer* SCIENCE VOL. 280 (12) JUNE

7 The top view of three layers at the neck showing atomic positions and their relative registry at different levels of stretch. m = 15 occurs before the first yielding stage. The atomic positions in the layers 2, 3 and 4 are indicated by +, and, respectively. m = 38 and m = 41 occur after the second yielding stage. m = 46, 47 and m = 49 show the formation of bundle structure (or strands). In the panels for m = the positions of atoms in the third, fourth and fifth (central) layers are indicated by +, and, respectively. Atomic chains in a bundle are highlighted by square boxes. [K. S. Ciraci, A. Buldum, I.P. Batra, Quantum effects in electrical and thermal transport through nanowires,

8 Figure 7-4: Variation of the conductance calculated for the stretching nanowire described in Figure 7-2. [K. S. Ciraci, A. Buldum, I.P. Batra, Quantum effects in electrical and thermal transport through nanowires, 2001, Journal of Physics Condensed Matter]

9 Carbon Nanotubes Electrical Properties 1D object (Quantum wire) Perfect structure, almost no phonons: Ballistic transport Nano: Single electronics, particle in a box High current density, excellent thermal properties FET, Diode, LEDs

10 Schematic illustrations of the structures of (A) armchair, (B) zigzag, and( C) chiral SWNTs.Projections normal to the tube axis andperspective views along the tube axis are on the top and bottom, respectively. (D) Tunneling electron microscope image (72) showing the helical structure of a 1.3-nm-diameter chiral SWNT. (E) Transmission electron microscope ( TEM) image of a MWNT containing a concentrically nestedarray of nine SWNTs. (F) TEM micrograph (18) showing the lateral packing of 1.4-nm-diameter SWNTs in a bundle. (G) Scanning electron microscope (SEM) image of an array of MWNTs grown as a nanotube forest. (VOL 297 SCIENCE 2002)

11 Figure 7-9: (a) A single-wall nanotube is graphene wrapped on a cylinder surface. (b) Nanotubes are described by a set of two integers (n, m) which indicate the graphite lattice vector components. A chiral vector can be defined as C = na1 + ma2. Tubes are called zigzag if either one of the integers is zero (n, 0) or called armchair if both integers are equal (n, n). [K. S. Ciraci, A. Buldum, I.P. Batra, Quantum effects in electrical and thermal transport through nanowires, 2001, Journal of Physics Condensed Matter]

12 CNT, electrical conductivity As a nanotube is in the form of a wrapped sheet of graphite, its electronic structure is analogous to the electronic structure of a graphene. Graphene has the lowest -conduction band and the highest -valence band, which are separated by a gap in the entire hexagonal Brillouin zone (BZ) except at its K corners where they cross. In this respect, graphene lies between a semiconductor and a metal with Fermi points at the corners of the BZ.

13 You can imagine an unrolled, open form of nanotube, which is graphene subject to periodic boundary conditions on the chiral vector. This in turn imposes quantization on the wave vector. A nanotube s electronic structure can thus be viewed as a zonefolded version of the electronic band structure of the graphene. When these parallel lines of nanotube wave vectors pass through the corners, the nanotube is metallic. Otherwise, the nanotube is a semiconductor with a gap of about 1 ev, which is reduced as the diameter of the tube increases. Within this simple approach, (n, m) nanotubes are metallic if n m = 3 integer. Consequently, all armchair tubes are metallic. The conclusion that you draw from the above paragraph is that the electronic structures of nanotubes are determined by their chirality and diameter, i.e. simply by their chiral vectors C.

14 Figure 7-10: (a) The band structure, (b) density of states and (c) conductance of a (10, 10) nanotube. The tight-binding model is used to derive the electronic structure. The conductance is calculated using the Green s function approach with the Landauer formalism. [K. S. Ciraci, A. Buldum, I.P. Batra, Quantum effects in electrical and thermal transport through nanowires, 2001, Journal of Physics Condensed Matter]

15 Ballistic transport Electron microscope image of an ensamble of MWNTs mounted on a motion stage realized by de Heer and co-workers at Georgia Tech. The MWNT sticking out most is progressively dipped into liquid mercury, which serves as a second electrode. De Heer and co-workers found that all multiwall nanotubes have nearly the same conductance, σ 0 = 2e 2 /h, and that the dependence of the resistance on length was very weak. In other words, multiwall nanotubes appeared to be ballistic conductors, despite the interactions expected between the different layers

16 Figure 7-15: (a) An intermolecular nanotube junction formed by bringing two semi-infinite (10, 10) tubes together. l is the contact length. (b) The conductance, G, of a (10, 10) (10, 10) junction as a function of energy, E, for l = 64 Å. Interference of electron waves yields resonances in conductance. (c) Current voltage characteristics of a (10, 10) (10, 10) junction at l = 46 Å. [K. S. Ciraci, A. Buldum, I.P. Batra, Quantum effects in electrical and thermal transport through nanowires, 2001, Journal of Physics Condensed Matter]

17 Figure 7-16: (a) A four-terminal cross-junction with two nanotubes perpendicular to each other. (b) The resistance of an (18, 0) (10, 10) junction as a function of tube rotation. The rotation angle,, and terminal indices are shown in the inset. The tube which is labelled by 2 and 4 is rotated by. The contact region structure is commensurate at = 30, 90, 150.[K. S. Ciraci, A. Buldum, I.P. Batra,

18 Field emission CNTs have excellent materials properties which make them have attractive field emission characteristics. Large aspect ratio(>1000) Atomically Sharp tips High temperature and chemical stability High electrical and thermal conductivity

19 A) Schematic illustration of a flat panel display based on carbon nanotubes. ITO, indium tin oxide. (B) SEM image (49) of an electron emitter for a display, showing well-separated SWNT bundles protruding from the supporting metal base. (C) Photograph of a 5-inch (13-cm) nanotube field emission display made by Samsung.

20 Nanotubes as Transistors Multiwalled nanotube ropes have varying electrical properties Electrical breakdown can be used to select the tube with correct properties Transistor tuning Ph. Avouris, Science

21 Nanoelectronic devices. (A) Schematic diagram (61) for a carbon NT-FET. (nanotube field emission transistor) The semiconducting nanotube, which is on top of an insulating aluminum oxide layer, is connected at both ends to gold electrodes. The nanotube is switched by applying a potential to the aluminum gate under the nanotube and aluminum oxide. (B) Scanning tunneling microscope (STM) picture of a SWNT field-effect transistor made using the design of (A). The aluminum strip is overcoated with aluminum oxide.

22 For single-electron devices one will try to build structures with few free carriers, to achieve a high change in energy when charging an island.

23 ÉCOLE POLYTECHNIQUE FÉDÉRALE DE LAUSANNE Coulomb Blockade metal particle oxide Coulomb Energy E C = e 2 /2C >k B T C > 12 nf at 80 K, 3 nf at RT C = 2πεd => d = 1 2 nm ε: permettivity of surrounding material Thershold voltage V th = e/c Small high resistance tunnel junctions -> small particles with small capacitance

24 Surface Plasmons Example: nanozised Gold Particles 10 nm

25 Definitions Surface plasmons are fluctuations in the electron density at the boundary of two materials. Plasmons are the collective vibrations of an electron gas (or plasma) surrounding the atomic lattice sites of a metal. When plasmons couple with a photon, the resulting particle is called a polariton. This polariton propagates along the surface of the metal until it decays, either by absorption, where upon the energy is converted into phonons, or by a radiative transition into a photon. The excitation of surface plasmons by light is denoted as a surface plasmon resonance (SPR) for planar surfaces or localized surface plasmon resonance (LSPR) for nanometer-sized metallic structures.

26 The Lycurgus Cup (glass; British Museum; 4 th century A. D.)

27

28 The potential is = A r sin cos inside the sphere (r < a) and = (-E o r + B/r²) sin cos outside the sphere (r > a), where A and B are constants to be determined. If these solutions are inserted into the boundary conditions and the resulting is used to determine the field outside the sphere, x 3x Eout = Eo x αeo ( xx + yy + zz) 3 5 r r (7. 162) We note that the first term in eq (7. 162) is the applied field and the second is the induced dipole field (induced dipole moment = E o ) that results from polarization of the conduction electron density. For a sphere with the dielectric constants indicated above, the LaPlace equation solution shows that the polarizability is (7. 163) with α = 3 g d a g d = i i (7. 164)

29 Although the dipole field in eq is that for a static dipole, the more complete Maxwell equation solution shows that this is actually a radiating dipole, and thus, it contributes to extinction and Rayleigh scattering by the sphere. This leads to extinction and scattering efficiencies given by (7. 165) Q ext = 4x Im( g d ) Q = 8 3 x 4 sca g d 2 (7. 166) where x = 2 a( 0 )1/2/. The efficiency is the ratio of the cross-section to the geometrical cross-section a².

30

31 Ordered structure at surfaces Gold 15nm particles (ph = 6, I c = 10-2 M) p = 50nm h = 65nm ph = 6 Ic = M Surface plasmons resonance

32 Photon STM Image of a Chain of Au nanoparticles [from Krenn et al, PRL 82, 2590 (1999)] Individual particles: 100x100x40 nm, separated by 100 nm and deposited on an ITO substrate. Sphere at end of waveguide is excited using the tip of near-field scanning optical microscope (NSOM), and wave is detected using fluorescent nanospheres.

33

34 J. M. Klostranec, W. C. W. Chan/Quantum Dots in Biological and Biomedical Research

35 Absorption spectra of CdS particles with increasing size 600 Absorption peak position (nm) Particle diameter (nm)

36

37

38

39 Alivisatos 1996 (A) A simplified MO diagram for the electronic structures of zinc blende CdSe and diamond structure Si. (B) A comparison of the HOMO-LUMO transitions for CdSe and Si. In CdSe the transition is dipole allowed, while in Si it is not.

40

41

42

43 Quantized Energy Levels The narrower the space, the smaller the crystal the larger the frequency & energy gap between those modes More confined spaces have wider energy gaps between their distinct momentum states. λ/3, 3E λ/2, 2E λ, E

44

45 two 2 3 4

46

47

48

49 Band gap engineering of semiconductors M is the reduced mass of the exciton, an electron-hole pair that behaves as one particle, since the motions of the electron and the hole are correlated. Quantum confinement effects are observed when the exciton Bohr radius is similiar to the nano-crystallite size R B Exciton Bohr radius M is the reduced exciton mass given by: 2 ε = ħ 1 = * * Me M me mh Increase in energy gap E = g 2 2 ħ π 2MR 2 nanocrystal Strongly-confined regime: D < 2R B Intermediate confinement regime: D ~ 2R B Weakly-confined regime: D > 2R B Crysta l Si Ge GaAs GaP InP CdS InSb R ( ) B nm

50 Molecular wire Before one can seriously discuss such electronic devices embedded in single molecules, one must deal with the question of whether a small single molecule can conduct appreciable current. Simulation,

51 Molecular RTD (resonant tunnel diode ) Structure and mechanism for possible molecular RTD proposed by Tour. Conducting chain molecule, but with insulating barrier groups that may generate potential well for quantum confinement that could create a resonant tunneling effect when the molecule is subjected to a voltage bias, permitting a current of electrons to be transmitted through the device.

52 MOLECULAR ELECTRONICS Molecular electronics uses primarily covalently bonded molecular structures, electrically isolated from a bulk substrate. Devices of this description, wires and switches composed of individual molecules and nanometer-scale supramolecular structures, sometimes are said to form the basis for an intramolecular electronics Molecular Electronic Switching Devices electric-field controlled molecular electronic switching devices, including molecular quantum-effect devices electromechanical molecular electronic devices, employing electrically or mechanically applied forces to change the conformation or to move a switching molecule or group of atoms to turn a current on and off; photoactive/photochromic molecular switching devices which use light to change the shape, orientation, or electron configuration of a molecule in order to switch a current; electrochemical molecular devices which use electrochemical reactions to change the shape, orientation, or electron configuration of a molecule and hence to switch a current.

53 Molecular Switch

54

55 energy E c E g E v Decreasing size E = E + E g, nanocrystal g, bulk g = E ħ π g, bulk 2 2MRnanocrystal Quantum confinement effects It is possible to engineer the electronic structure of a material, by reducing the crystal size.

56

57 D(E) 3D Bulk 2D Quantum film 1D Quantum wire 0D Quantum dot

Electrical and Optical Properties. H.Hofmann

Electrical and Optical Properties. H.Hofmann Introduction to Nanomaterials Electrical and Optical Properties H.Hofmann Electrical Properties Ohm: G= σw/l where is the length of the conductor, measured in meters [m], A is the cross-section area of

More information

Quantized Electrical Conductance of Carbon nanotubes(cnts)

Quantized Electrical Conductance of Carbon nanotubes(cnts) Quantized Electrical Conductance of Carbon nanotubes(cnts) By Boxiao Chen PH 464: Applied Optics Instructor: Andres L arosa Abstract One of the main factors that impacts the efficiency of solar cells is

More information

Graphene and Carbon Nanotubes

Graphene and Carbon Nanotubes Graphene and Carbon Nanotubes 1 atom thick films of graphite atomic chicken wire Novoselov et al - Science 306, 666 (004) 100μm Geim s group at Manchester Novoselov et al - Nature 438, 197 (005) Kim-Stormer

More information

Chapter 3 Properties of Nanostructures

Chapter 3 Properties of Nanostructures Chapter 3 Properties of Nanostructures In Chapter 2, the reduction of the extent of a solid in one or more dimensions was shown to lead to a dramatic alteration of the overall behavior of the solids. Generally,

More information

Nanophysics: Main trends

Nanophysics: Main trends Nano-opto-electronics Nanophysics: Main trends Nanomechanics Main issues Light interaction with small structures Molecules Nanoparticles (semiconductor and metallic) Microparticles Photonic crystals Nanoplasmonics

More information

The Dielectric Function of a Metal ( Jellium )

The Dielectric Function of a Metal ( Jellium ) The Dielectric Function of a Metal ( Jellium ) Total reflection Plasma frequency p (10 15 Hz range) Why are Metals Shiny? An electric field cannot exist inside a metal, because metal electrons follow the

More information

2 Symmetry. 2.1 Structure of carbon nanotubes

2 Symmetry. 2.1 Structure of carbon nanotubes 2 Symmetry Carbon nanotubes are hollow cylinders of graphite sheets. They can be viewed as single molecules, regarding their small size ( nm in diameter and µm length), or as quasi-one dimensional crystals

More information

Carbon based Nanoscale Electronics

Carbon based Nanoscale Electronics Carbon based Nanoscale Electronics 09 02 200802 2008 ME class Outline driving force for the carbon nanomaterial electronic properties of fullerene exploration of electronic carbon nanotube gold rush of

More information

Introduction to Nanotechnology Chapter 5 Carbon Nanostructures Lecture 1

Introduction to Nanotechnology Chapter 5 Carbon Nanostructures Lecture 1 Introduction to Nanotechnology Chapter 5 Carbon Nanostructures Lecture 1 ChiiDong Chen Institute of Physics, Academia Sinica chiidong@phys.sinica.edu.tw 02 27896766 Section 5.2.1 Nature of the Carbon Bond

More information

In today s lecture, we will cover:

In today s lecture, we will cover: In today s lecture, we will cover: Metal and Metal oxide Nanoparticles Semiconductor Nanocrystals Carbon Nanotubes 1 Week 2: Nanoparticles Goals for this section Develop an understanding of the physical

More information

Carbon nanotubes in a nutshell. Graphite band structure. What is a carbon nanotube? Start by considering graphite.

Carbon nanotubes in a nutshell. Graphite band structure. What is a carbon nanotube? Start by considering graphite. Carbon nanotubes in a nutshell What is a carbon nanotube? Start by considering graphite. sp 2 bonded carbon. Each atom connected to 3 neighbors w/ 120 degree bond angles. Hybridized π bonding across whole

More information

Metallic: 2n 1. +n 2. =3q Armchair structure always metallic = 2

Metallic: 2n 1. +n 2. =3q Armchair structure always metallic = 2 Properties of CNT d = 2.46 n 2 2 1 + n1n2 + n2 2π Metallic: 2n 1 +n 2 =3q Armchair structure always metallic a) Graphite Valence(π) and Conduction(π*) states touch at six points(fermi points) Carbon Nanotube:

More information

Nanostructures. Lecture 13 OUTLINE

Nanostructures. Lecture 13 OUTLINE Nanostructures MTX9100 Nanomaterials Lecture 13 OUTLINE -What is quantum confinement? - How can zero-dimensional materials be used? -What are one dimensional structures? -Why does graphene attract so much

More information

Lecture 20: Semiconductor Structures Kittel Ch 17, p , extra material in the class notes

Lecture 20: Semiconductor Structures Kittel Ch 17, p , extra material in the class notes Lecture 20: Semiconductor Structures Kittel Ch 17, p 494-503, 507-511 + extra material in the class notes MOS Structure Layer Structure metal Oxide insulator Semiconductor Semiconductor Large-gap Semiconductor

More information

Nanoelectronics. Topics

Nanoelectronics. Topics Nanoelectronics Topics Moore s Law Inorganic nanoelectronic devices Resonant tunneling Quantum dots Single electron transistors Motivation for molecular electronics The review article Overview of Nanoelectronic

More information

Chapter 1 Overview of Semiconductor Materials and Physics

Chapter 1 Overview of Semiconductor Materials and Physics Chapter 1 Overview of Semiconductor Materials and Physics Professor Paul K. Chu Conductivity / Resistivity of Insulators, Semiconductors, and Conductors Semiconductor Elements Period II III IV V VI 2 B

More information

Carbon nanotubes in a nutshell

Carbon nanotubes in a nutshell Carbon nanotubes in a nutshell What is a carbon nanotube? Start by considering graphite. sp 2 bonded carbon. Each atom connected to 3 neighbors w/ 120 degree bond angles. Hybridized π bonding across whole

More information

Carbon Nanotubes in Interconnect Applications

Carbon Nanotubes in Interconnect Applications Carbon Nanotubes in Interconnect Applications Page 1 What are Carbon Nanotubes? What are they good for? Why are we interested in them? - Interconnects of the future? Comparison of electrical properties

More information

CME 300 Properties of Materials. ANSWERS: Homework 9 November 26, As atoms approach each other in the solid state the quantized energy states:

CME 300 Properties of Materials. ANSWERS: Homework 9 November 26, As atoms approach each other in the solid state the quantized energy states: CME 300 Properties of Materials ANSWERS: Homework 9 November 26, 2011 As atoms approach each other in the solid state the quantized energy states: are split. This splitting is associated with the wave

More information

OPTICAL PROPERTIES of Nanomaterials

OPTICAL PROPERTIES of Nanomaterials OPTICAL PROPERTIES of Nanomaterials Advanced Reading Optical Properties and Spectroscopy of Nanomaterials Jin Zhong Zhang World Scientific, Singapore, 2009. Optical Properties Many of the optical properties

More information

Introduction to Molecular Electronics. Lecture 1: Basic concepts

Introduction to Molecular Electronics. Lecture 1: Basic concepts Introduction to Molecular Electronics Lecture 1: Basic concepts Conductive organic molecules Plastic can indeed, under certain circumstances, be made to behave very like a metal - a discovery for which

More information

EN2912C: Future Directions in Computing Lecture 08: Overview of Near-Term Emerging Computing Technologies

EN2912C: Future Directions in Computing Lecture 08: Overview of Near-Term Emerging Computing Technologies EN2912C: Future Directions in Computing Lecture 08: Overview of Near-Term Emerging Computing Technologies Prof. Sherief Reda Division of Engineering Brown University Fall 2008 1 Near-term emerging computing

More information

Lecture 3: Heterostructures, Quasielectric Fields, and Quantum Structures

Lecture 3: Heterostructures, Quasielectric Fields, and Quantum Structures Lecture 3: Heterostructures, Quasielectric Fields, and Quantum Structures MSE 6001, Semiconductor Materials Lectures Fall 2006 3 Semiconductor Heterostructures A semiconductor crystal made out of more

More information

Introduction to semiconductor nanostructures. Peter Kratzer Modern Concepts in Theoretical Physics: Part II Lecture Notes

Introduction to semiconductor nanostructures. Peter Kratzer Modern Concepts in Theoretical Physics: Part II Lecture Notes Introduction to semiconductor nanostructures Peter Kratzer Modern Concepts in Theoretical Physics: Part II Lecture Notes What is a semiconductor? The Fermi level (chemical potential of the electrons) falls

More information

Spectroscopy at nanometer scale

Spectroscopy at nanometer scale Spectroscopy at nanometer scale 1. Physics of the spectroscopies 2. Spectroscopies for the bulk materials 3. Experimental setups for the spectroscopies 4. Physics and Chemistry of nanomaterials Various

More information

Plasmonics. The long wavelength of light ( μm) creates a problem for extending optoelectronics into the nanometer regime.

Plasmonics. The long wavelength of light ( μm) creates a problem for extending optoelectronics into the nanometer regime. Plasmonics The long wavelength of light ( μm) creates a problem for extending optoelectronics into the nanometer regime. A possible way out is the conversion of light into plasmons. They have much shorter

More information

Carbon Nanotubes (CNTs)

Carbon Nanotubes (CNTs) Carbon Nanotubes (s) Seminar: Quantendynamik in mesoskopischen Systemen Florian Figge Fakultät für Physik Albert-Ludwigs-Universität Freiburg July 7th, 2010 F. Figge (University of Freiburg) Carbon Nanotubes

More information

single-electron electron tunneling (SET)

single-electron electron tunneling (SET) single-electron electron tunneling (SET) classical dots (SET islands): level spacing is NOT important; only the charging energy (=classical effect, many electrons on the island) quantum dots: : level spacing

More information

Nanomaterials and their Optical Applications

Nanomaterials and their Optical Applications Nanomaterials and their Optical Applications Winter Semester 2013 Lecture 02 rachel.grange@uni-jena.de http://www.iap.uni-jena.de/multiphoton Lecture 2: outline 2 Introduction to Nanophotonics Theoretical

More information

ELECTRONIC DEVICES AND CIRCUITS SUMMARY

ELECTRONIC DEVICES AND CIRCUITS SUMMARY ELECTRONIC DEVICES AND CIRCUITS SUMMARY Classification of Materials: Insulator: An insulator is a material that offers a very low level (or negligible) of conductivity when voltage is applied. Eg: Paper,

More information

Localized surface plasmons (Particle plasmons)

Localized surface plasmons (Particle plasmons) Localized surface plasmons (Particle plasmons) ( Plasmons in metal nanostructures, Dissertation, University of Munich by Carsten Sonnichsen, 2001) Lycurgus cup, 4th century (now at the British Museum,

More information

chiral m = n Armchair m = 0 or n = 0 Zigzag m n Chiral Three major categories of nanotube structures can be identified based on the values of m and n

chiral m = n Armchair m = 0 or n = 0 Zigzag m n Chiral Three major categories of nanotube structures can be identified based on the values of m and n zigzag armchair Three major categories of nanotube structures can be identified based on the values of m and n m = n Armchair m = 0 or n = 0 Zigzag m n Chiral Nature 391, 59, (1998) chiral J. Tersoff,

More information

Nanomaterials and their Optical Applications

Nanomaterials and their Optical Applications Nanomaterials and their Optical Applications Winter Semester 2012 Lecture 04 rachel.grange@uni-jena.de http://www.iap.uni-jena.de/multiphoton Lecture 4: outline 2 Characterization of nanomaterials SEM,

More information

ELEC 4700 Assignment #2

ELEC 4700 Assignment #2 ELEC 4700 Assignment #2 Question 1 (Kasop 4.2) Molecular Orbitals and Atomic Orbitals Consider a linear chain of four identical atoms representing a hypothetical molecule. Suppose that each atomic wavefunction

More information

Electric Field-Dependent Charge-Carrier Velocity in Semiconducting Carbon. Nanotubes. Yung-Fu Chen and M. S. Fuhrer

Electric Field-Dependent Charge-Carrier Velocity in Semiconducting Carbon. Nanotubes. Yung-Fu Chen and M. S. Fuhrer Electric Field-Dependent Charge-Carrier Velocity in Semiconducting Carbon Nanotubes Yung-Fu Chen and M. S. Fuhrer Department of Physics and Center for Superconductivity Research, University of Maryland,

More information

Carbon Nanomaterials

Carbon Nanomaterials Carbon Nanomaterials STM Image 7 nm AFM Image Fullerenes C 60 was established by mass spectrographic analysis by Kroto and Smalley in 1985 C 60 is called a buckminsterfullerene or buckyball due to resemblance

More information

Introduction to Nanotechnology Chapter 5 Carbon Nanostructures Lecture 1

Introduction to Nanotechnology Chapter 5 Carbon Nanostructures Lecture 1 Introduction to Nanotechnology Chapter 5 Carbon Nanostructures Lecture 1 ChiiDong Chen Institute of Physics, Academia Sinica chiidong@phys.sinica.edu.tw 02 27896766 Carbon contains 6 electrons: (1s) 2,

More information

Nanoscale optical circuits: controlling light using localized surface plasmon resonances

Nanoscale optical circuits: controlling light using localized surface plasmon resonances Nanoscale optical circuits: controlling light using localized surface plasmon resonances T. J. Davis, D. E. Gómez and K. C. Vernon CSIRO Materials Science and Engineering Localized surface plasmon (LSP)

More information

3-month progress Report

3-month progress Report 3-month progress Report Graphene Devices and Circuits Supervisor Dr. P.A Childs Table of Content Abstract... 1 1. Introduction... 1 1.1 Graphene gold rush... 1 1.2 Properties of graphene... 3 1.3 Semiconductor

More information

Optical Properties of Lattice Vibrations

Optical Properties of Lattice Vibrations Optical Properties of Lattice Vibrations For a collection of classical charged Simple Harmonic Oscillators, the dielectric function is given by: Where N i is the number of oscillators with frequency ω

More information

Supplementary Figure S1. AFM images of GraNRs grown with standard growth process. Each of these pictures show GraNRs prepared independently,

Supplementary Figure S1. AFM images of GraNRs grown with standard growth process. Each of these pictures show GraNRs prepared independently, Supplementary Figure S1. AFM images of GraNRs grown with standard growth process. Each of these pictures show GraNRs prepared independently, suggesting that the results is reproducible. Supplementary Figure

More information

Calculating Electronic Structure of Different Carbon Nanotubes and its Affect on Band Gap

Calculating Electronic Structure of Different Carbon Nanotubes and its Affect on Band Gap Calculating Electronic Structure of Different Carbon Nanotubes and its Affect on Band Gap 1 Rashid Nizam, 2 S. Mahdi A. Rizvi, 3 Ameer Azam 1 Centre of Excellence in Material Science, Applied Physics AMU,

More information

Electron Interactions and Nanotube Fluorescence Spectroscopy C.L. Kane & E.J. Mele

Electron Interactions and Nanotube Fluorescence Spectroscopy C.L. Kane & E.J. Mele Electron Interactions and Nanotube Fluorescence Spectroscopy C.L. Kane & E.J. Mele Large radius theory of optical transitions in semiconducting nanotubes derived from low energy theory of graphene Phys.

More information

From nanophysics research labs to cell phones. Dr. András Halbritter Department of Physics associate professor

From nanophysics research labs to cell phones. Dr. András Halbritter Department of Physics associate professor From nanophysics research labs to cell phones Dr. András Halbritter Department of Physics associate professor Curriculum Vitae Birth: 1976. High-school graduation: 1994. Master degree: 1999. PhD: 2003.

More information

7. Localized surface plasmons (Particle plasmons)

7. Localized surface plasmons (Particle plasmons) 7. Localized surface plasmons (Particle plasmons) ( Plasmons in metal nanostructures, Dissertation, University of Munich by Carsten Sonnichsen, 2001) Lycurgus cup, 4th century (now at the British Museum,

More information

Quantised Thermal Conductance

Quantised Thermal Conductance B B Quantised Thermal Conductance In 1983 J Pendry published a paper on the quantum limits to the flow of information and entropy [Pendry'83]. In it he showed that there is an inequality that limits the

More information

Semiconductor Nanowires: Motivation

Semiconductor Nanowires: Motivation Semiconductor Nanowires: Motivation Patterning into sub 50 nm range is difficult with optical lithography. Self-organized growth of nanowires enables 2D confinement of carriers with large splitting of

More information

CITY UNIVERSITY OF HONG KONG. Theoretical Study of Electronic and Electrical Properties of Silicon Nanowires

CITY UNIVERSITY OF HONG KONG. Theoretical Study of Electronic and Electrical Properties of Silicon Nanowires CITY UNIVERSITY OF HONG KONG Ë Theoretical Study of Electronic and Electrical Properties of Silicon Nanowires u Ä öä ªqk u{ Submitted to Department of Physics and Materials Science gkö y in Partial Fulfillment

More information

Carbon Nanotube: Property, application and ultrafast optical spectroscopy

Carbon Nanotube: Property, application and ultrafast optical spectroscopy Carbon Nanotube: Property, application and ultrafast optical spectroscopy Yijing Fu 1, Qing Yu 1 Institute of Optics, University of Rochester Department of Electrical engineering, University of Rochester

More information

Plasmonic Photovoltaics Harry A. Atwater California Institute of Technology

Plasmonic Photovoltaics Harry A. Atwater California Institute of Technology Plasmonic Photovoltaics Harry A. Atwater California Institute of Technology Surface plasmon polaritons and localized surface plasmons Plasmon propagation and absorption at metal-semiconductor interfaces

More information

CHAPTER 6 CHIRALITY AND SIZE EFFECT IN SINGLE WALLED CARBON NANOTUBES

CHAPTER 6 CHIRALITY AND SIZE EFFECT IN SINGLE WALLED CARBON NANOTUBES 10 CHAPTER 6 CHIRALITY AND SIZE EFFECT IN SINGLE WALLED CARBON NANOTUBES 6.1 PREAMBLE Lot of research work is in progress to investigate the properties of CNTs for possible technological applications.

More information

Seminars in Nanosystems - I

Seminars in Nanosystems - I Seminars in Nanosystems - I Winter Semester 2011/2012 Dr. Emanuela Margapoti Emanuela.Margapoti@wsi.tum.de Dr. Gregor Koblmüller Gregor.Koblmueller@wsi.tum.de Seminar Room at ZNN 1 floor Topics of the

More information

NANO/MICROSCALE HEAT TRANSFER

NANO/MICROSCALE HEAT TRANSFER NANO/MICROSCALE HEAT TRANSFER Zhuomin M. Zhang Georgia Institute of Technology Atlanta, Georgia New York Chicago San Francisco Lisbon London Madrid Mexico City Milan New Delhi San Juan Seoul Singapore

More information

Classification of Solids

Classification of Solids Classification of Solids Classification by conductivity, which is related to the band structure: (Filled bands are shown dark; D(E) = Density of states) Class Electron Density Density of States D(E) Examples

More information

Lecture 20 - Semiconductor Structures

Lecture 20 - Semiconductor Structures Lecture 0: Structures Kittel Ch 17, p 494-503, 507-511 + extra material in the class notes MOS Structure metal Layer Structure Physics 460 F 006 Lect 0 1 Outline What is a semiconductor Structure? Created

More information

Chapter 4: Bonding in Solids and Electronic Properties. Free electron theory

Chapter 4: Bonding in Solids and Electronic Properties. Free electron theory Chapter 4: Bonding in Solids and Electronic Properties Free electron theory Consider free electrons in a metal an electron gas. regards a metal as a box in which electrons are free to move. assumes nuclei

More information

Spectroscopy at nanometer scale

Spectroscopy at nanometer scale Spectroscopy at nanometer scale 1. Physics of the spectroscopies 2. Spectroscopies for the bulk materials 3. Experimental setups for the spectroscopies 4. Physics and Chemistry of nanomaterials Various

More information

SOLID STATE PHYSICS. Second Edition. John Wiley & Sons. J. R. Hook H. E. Hall. Department of Physics, University of Manchester

SOLID STATE PHYSICS. Second Edition. John Wiley & Sons. J. R. Hook H. E. Hall. Department of Physics, University of Manchester SOLID STATE PHYSICS Second Edition J. R. Hook H. E. Hall Department of Physics, University of Manchester John Wiley & Sons CHICHESTER NEW YORK BRISBANE TORONTO SINGAPORE Contents Flow diagram Inside front

More information

Imaging Methods: Scanning Force Microscopy (SFM / AFM)

Imaging Methods: Scanning Force Microscopy (SFM / AFM) Imaging Methods: Scanning Force Microscopy (SFM / AFM) The atomic force microscope (AFM) probes the surface of a sample with a sharp tip, a couple of microns long and often less than 100 Å in diameter.

More information

VALLIAMMAI ENGINEERING COLLEGE

VALLIAMMAI ENGINEERING COLLEGE VALLIAMMAI ENGINEERING COLLEGE SRM Nagar, Kattankulathur 603 203 DEPARTMENT OF PHYSICS QUESTION BANK II SEMESTER PH8252 - PHYSICS FOR INFORMATION SCIENCE (Common to CSE & IT) Regulation 2017 Academic Year

More information

Electrostatics of Nanowire Transistors

Electrostatics of Nanowire Transistors Electrostatics of Nanowire Transistors Jing Guo, Jing Wang, Eric Polizzi, Supriyo Datta and Mark Lundstrom School of Electrical and Computer Engineering Purdue University, West Lafayette, IN, 47907 ABSTRACTS

More information

STM spectroscopy (STS)

STM spectroscopy (STS) STM spectroscopy (STS) di dv 4 e ( E ev, r) ( E ) M S F T F Basic concepts of STS. With the feedback circuit open the variation of the tunneling current due to the application of a small oscillating voltage

More information

what happens if we make materials smaller?

what happens if we make materials smaller? what happens if we make materials smaller? IAP VI/10 ummer chool 2007 Couvin Prof. ns outline Introduction making materials smaller? ynthesis how do you make nanomaterials? Properties why would you make

More information

Physics of Semiconductors (Problems for report)

Physics of Semiconductors (Problems for report) Physics of Semiconductors (Problems for report) Shingo Katsumoto Institute for Solid State Physics, University of Tokyo July, 0 Choose two from the following eight problems and solve them. I. Fundamentals

More information

Nanoscience, MCC026 2nd quarter, fall Quantum Transport, Lecture 1/2. Tomas Löfwander Applied Quantum Physics Lab

Nanoscience, MCC026 2nd quarter, fall Quantum Transport, Lecture 1/2. Tomas Löfwander Applied Quantum Physics Lab Nanoscience, MCC026 2nd quarter, fall 2012 Quantum Transport, Lecture 1/2 Tomas Löfwander Applied Quantum Physics Lab Quantum Transport Nanoscience: Quantum transport: control and making of useful things

More information

1 Name: Student number: DEPARTMENT OF PHYSICS AND PHYSICAL OCEANOGRAPHY MEMORIAL UNIVERSITY OF NEWFOUNDLAND. Fall :00-11:00

1 Name: Student number: DEPARTMENT OF PHYSICS AND PHYSICAL OCEANOGRAPHY MEMORIAL UNIVERSITY OF NEWFOUNDLAND. Fall :00-11:00 1 Name: DEPARTMENT OF PHYSICS AND PHYSICAL OCEANOGRAPHY MEMORIAL UNIVERSITY OF NEWFOUNDLAND Final Exam Physics 3000 December 11, 2012 Fall 2012 9:00-11:00 INSTRUCTIONS: 1. Answer all seven (7) questions.

More information

Conductivity and Semi-Conductors

Conductivity and Semi-Conductors Conductivity and Semi-Conductors J = current density = I/A E = Electric field intensity = V/l where l is the distance between two points Metals: Semiconductors: Many Polymers and Glasses 1 Electrical Conduction

More information

Black phosphorus: A new bandgap tuning knob

Black phosphorus: A new bandgap tuning knob Black phosphorus: A new bandgap tuning knob Rafael Roldán and Andres Castellanos-Gomez Modern electronics rely on devices whose functionality can be adjusted by the end-user with an external knob. A new

More information

THEORETICAL STUDY OF THE QUANTUM CONFINEMENT EFFECTS ON QUANTUM DOTS USING PARTICLE IN A BOX MODEL

THEORETICAL STUDY OF THE QUANTUM CONFINEMENT EFFECTS ON QUANTUM DOTS USING PARTICLE IN A BOX MODEL Journal of Ovonic Research Vol. 14, No. 1, January - February 2018, p. 49-54 THEORETICAL STUDY OF THE QUANTUM CONFINEMENT EFFECTS ON QUANTUM DOTS USING PARTICLE IN A BOX MODEL A. I. ONYIA *, H. I. IKERI,

More information

Physics and Material Science of Semiconductor Nanostructures

Physics and Material Science of Semiconductor Nanostructures Physics and Material Science of Semiconductor Nanostructures PHYS 570P Prof. Oana Malis Email: omalis@purdue.edu Course website: http://www.physics.purdue.edu/academic_programs/courses/phys570p/ 1 Introduction

More information

5 Problems Chapter 5: Electrons Subject to a Periodic Potential Band Theory of Solids

5 Problems Chapter 5: Electrons Subject to a Periodic Potential Band Theory of Solids E n = :75, so E cont = E E n = :75 = :479. Using E =!, :479 = m e k z =! j e j m e k z! k z = r :479 je j m e = :55 9 (44) (v g ) z = @! @k z = m e k z = m e :55 9 = :95 5 m/s. 4.. A ev electron is to

More information

2) Atom manipulation. Xe / Ni(110) Model: Experiment:

2) Atom manipulation. Xe / Ni(110) Model: Experiment: 2) Atom manipulation D. Eigler & E. Schweizer, Nature 344, 524 (1990) Xe / Ni(110) Model: Experiment: G.Meyer, et al. Applied Physics A 68, 125 (1999) First the tip is approached close to the adsorbate

More information

GRAPHENE the first 2D crystal lattice

GRAPHENE the first 2D crystal lattice GRAPHENE the first 2D crystal lattice dimensionality of carbon diamond, graphite GRAPHENE realized in 2004 (Novoselov, Science 306, 2004) carbon nanotubes fullerenes, buckyballs what s so special about

More information

Modern Physics for Frommies IV The Universe - Small to Large Lecture 4

Modern Physics for Frommies IV The Universe - Small to Large Lecture 4 Fromm Institute for Lifelong Learning University of San Francisco Modern Physics for Frommies IV The Universe - Small to Large Lecture 4 3 February 06 Modern Physics IV Lecture 4 Agenda Administrative

More information

Recap (so far) Low-Dimensional & Boundary Effects

Recap (so far) Low-Dimensional & Boundary Effects Recap (so far) Ohm s & Fourier s Laws Mobility & Thermal Conductivity Heat Capacity Wiedemann-Franz Relationship Size Effects and Breakdown of Classical Laws 1 Low-Dimensional & Boundary Effects Energy

More information

Optical Properties of Solid from DFT

Optical Properties of Solid from DFT Optical Properties of Solid from DFT 1 Prof.P. Ravindran, Department of Physics, Central University of Tamil Nadu, India & Center for Materials Science and Nanotechnology, University of Oslo, Norway http://folk.uio.no/ravi/cmt15

More information

Graphene. Tianyu Ye November 30th, 2011

Graphene. Tianyu Ye November 30th, 2011 Graphene Tianyu Ye November 30th, 2011 Outline What is graphene? How to make graphene? (Exfoliation, Epitaxial, CVD) Is it graphene? (Identification methods) Transport properties; Other properties; Applications;

More information

Electro - Principles I

Electro - Principles I Electro - Principles I Page 10-1 Atomic Theory It is necessary to know what goes on at the atomic level of a semiconductor so the characteristics of the semiconductor can be understood. In many cases a

More information

ELEMENTARY BAND THEORY

ELEMENTARY BAND THEORY ELEMENTARY BAND THEORY PHYSICIST Solid state band Valence band, VB Conduction band, CB Fermi energy, E F Bloch orbital, delocalized n-doping p-doping Band gap, E g Direct band gap Indirect band gap Phonon

More information

smal band gap Saturday, April 9, 2011

smal band gap Saturday, April 9, 2011 small band gap upper (conduction) band empty small gap valence band filled 2s 2p 2s 2p hybrid (s+p)band 2p no gap 2s (depend on the crystallographic orientation) extrinsic semiconductor semi-metal electron

More information

PH575 Spring Lecture #28 Nanoscience: the case study of graphene and carbon nanotubes.

PH575 Spring Lecture #28 Nanoscience: the case study of graphene and carbon nanotubes. PH575 Spring 2014 Lecture #28 Nanoscience: the case study of graphene and carbon nanotubes. Nanoscience scale 1-100 nm "Artificial atoms" Small size => discrete states Large surface to volume ratio Bottom-up

More information

UNIT I: Electronic Materials.

UNIT I: Electronic Materials. SIDDHARTH INSTITUTE OF ENGINEERING & TECHNOLOGY :: PUTTUR Siddharth Nagar, Narayanavanam Road 517583 QUESTION BANK (DESCRIPTIVE) Subject with Code: SEMICONDUCTOR PHYSICS (18HS0851) Course & Branch: B.Tech

More information

Lecture 2: Background dconcepts

Lecture 2: Background dconcepts Optoelectronics I Lecture : Background dconcepts M. Soroosh Assistant Professor of Electronics Shahid Chamran University 1 Face Centered Crystal (FCC) Body Centered Crystal (BCC) Bragg s Law William Lawrence

More information

Quantum Phenomena & Nanotechnology (4B5)

Quantum Phenomena & Nanotechnology (4B5) Quantum Phenomena & Nanotechnology (4B5) The 2-dimensional electron gas (2DEG), Resonant Tunneling diodes, Hot electron transistors Lecture 11 In this lecture, we are going to look at 2-dimensional electron

More information

Final exam. Introduction to Nanotechnology. Name: Student number:

Final exam. Introduction to Nanotechnology. Name: Student number: 1 Final exam. Introduction to Nanotechnology Name: Student number: 1. (a) What is the definition for a cluster size-wise? (3%) (b) Calculate the energy separation near the Fermi surface of a metallic cluster

More information

Electroluminescence from Silicon and Germanium Nanostructures

Electroluminescence from Silicon and Germanium Nanostructures Electroluminescence from silicon Silicon Getnet M. and Ghoshal S.K 35 ORIGINAL ARTICLE Electroluminescence from Silicon and Germanium Nanostructures Getnet Melese* and Ghoshal S. K.** Abstract Silicon

More information

Luminescence Process

Luminescence Process Luminescence Process The absorption and the emission are related to each other and they are described by two terms which are complex conjugate of each other in the interaction Hamiltonian (H er ). In an

More information

Fabrication / Synthesis Techniques

Fabrication / Synthesis Techniques Quantum Dots Physical properties Fabrication / Synthesis Techniques Applications Handbook of Nanoscience, Engineering, and Technology Ch.13.3 L. Kouwenhoven and C. Marcus, Physics World, June 1998, p.35

More information

The Physics of Nanoelectronics

The Physics of Nanoelectronics The Physics of Nanoelectronics Transport and Fluctuation Phenomena at Low Temperatures Tero T. Heikkilä Low Temperature Laboratory, Aalto University, Finland OXFORD UNIVERSITY PRESS Contents List of symbols

More information

Electronic transport in low dimensional systems

Electronic transport in low dimensional systems Electronic transport in low dimensional systems For example: 2D system l

More information

Use of Multi-Walled Carbon Nanotubes for UV radiation detection

Use of Multi-Walled Carbon Nanotubes for UV radiation detection Use of Multi-Walled Carbon Nanotubes for UV radiation detection Viviana Carillo 11th Topical Seminar on Innovative Particle and Radiation Detectors (IPRD08) 1-4 October 2008 Siena, Italy A new nanostructured

More information

Review of Optical Properties of Materials

Review of Optical Properties of Materials Review of Optical Properties of Materials Review of optics Absorption in semiconductors: qualitative discussion Derivation of Optical Absorption Coefficient in Direct Semiconductors Photons When dealing

More information

Review of Semiconductor Physics

Review of Semiconductor Physics Solid-state physics Review of Semiconductor Physics The daunting task of solid state physics Quantum mechanics gives us the fundamental equation The equation is only analytically solvable for a handful

More information

OPTI510R: Photonics. Khanh Kieu College of Optical Sciences, University of Arizona Meinel building R.626

OPTI510R: Photonics. Khanh Kieu College of Optical Sciences, University of Arizona Meinel building R.626 OPTI510R: Photonics Khanh Kieu College of Optical Sciences, University of Arizona kkieu@optics.arizona.edu Meinel building R.626 Announcements HW#3 is assigned due Feb. 20 st Mid-term exam Feb 27, 2PM

More information

The many forms of carbon

The many forms of carbon The many forms of carbon Carbon is not only the basis of life, it also provides an enormous variety of structures for nanotechnology. This versatility is connected to the ability of carbon to form two

More information

Minimal Update of Solid State Physics

Minimal Update of Solid State Physics Minimal Update of Solid State Physics It is expected that participants are acquainted with basics of solid state physics. Therefore here we will refresh only those aspects, which are absolutely necessary

More information

Nanotechnology. Yung Liou P601 Institute of Physics Academia Sinica

Nanotechnology. Yung Liou P601 Institute of Physics Academia Sinica Nanotechnology Yung Liou P601 yung@phys.sinica.edu.tw Institute of Physics Academia Sinica 1 1st week Definition of Nanotechnology The Interagency Subcommittee on Nanoscale Science, Engineering and Technology

More information

Quantum Confinement in Graphene

Quantum Confinement in Graphene Quantum Confinement in Graphene from quasi-localization to chaotic billards MMM dominikus kölbl 13.10.08 1 / 27 Outline some facts about graphene quasibound states in graphene numerical calculation of

More information

Sheng S. Li. Semiconductor Physical Electronics. Second Edition. With 230 Figures. 4) Springer

Sheng S. Li. Semiconductor Physical Electronics. Second Edition. With 230 Figures. 4) Springer Sheng S. Li Semiconductor Physical Electronics Second Edition With 230 Figures 4) Springer Contents Preface 1. Classification of Solids and Crystal Structure 1 1.1 Introduction 1 1.2 The Bravais Lattice

More information

GRAPHENE NANORIBBONS Nahid Shayesteh,

GRAPHENE NANORIBBONS Nahid Shayesteh, USC Department of Physics Graduate Seminar 1 GRAPHENE NANORIBBONS Nahid Shayesteh, Outlines 2 Carbon based material Discovery and innovation of graphen Graphene nanoribbons structure Application of Graphene

More information