Building a more complex molecule C 2

Building a more complex moleculeC2

Isolated impurities

From E. A. Moore: “Molecular Modelling and bonding”, Royal Soc. Chem.

Building a solid Graphite/Diamond

Isolated impurities

From W. A. Harrison: “Electron Structure” Royal Soc. Chem.

Building a metal (Copper)

Isolated impurities

From J. A. Burdick Phys. Rev. 129 138 (1963)

Isolatedatoms

CondensedPhase

ConductionBand

ValenceBand

AvailableStates

No Statesavailable

1/R

EBuilding a Semiconductor

Valence band

Conduction band

Isolated impurities

Fill up the states with electrons just like you fill up atomic or molecular states, fill from the lower energy up being careful to abide by Pauli.The material properties are dominated at by the highest energy states that are occupied.

Localized states near impurities; These control the properties of the semiconductor

Impurities in Semiconductors•“Electrons” in solids can behave as if they have a different mass and charge than free electrons. Why, the dynamics of the material are really determined by the “excitations” of the system (how it’s behaviour differs from the equilibrium state).•E.G. for Donors in Si you might expect E=(o/)2(m*/mo)EH

•For Si this works out to be about 25meV, and this is in reasonable agreement with the experimental results for shallow donors (even though we have left out a lot of details that account for differences between elements like P and As etc.

Band structure and Impurties in Si and Ge

From S. SM .Sze “Physics of Semiconductor devices”, Wiley (1969))

Nano Technology/Materials•Why interesting?

•Technological Applications (7 responses)•How do we make things that small? (8 responses)•Confinement energy becomes important (DVB)

•What would you like to hear more about?•Quantum computing (7 responses)•Applications in general (5 responses) life sciences (4)•Buckyballs/Carbon Nanotubes (5 responses)•How to make them? (4 responses)

Key Properties of Materials• Electrical Conductivity• Hall Effect (balance of Lorentz and Electric forces within

a wire carrying a current in a magnetic field).– Useful for measuring carrier concentration and type

(electrons vs. holes)– Ubiquitous for measuring magnetic fields

• Thermo-electric Effects– Electrons carry both charge and energy, hence the

two can be coupled.– Used widely for measuring temperature

• Piezoelectric effects (strain<-> voltages)– Used in SPM’s, small sensors etc.

Lecture 32Semiconductor Laser

http://www.explainthatstuff.com/laserdiode.png

The Field-Effect Transistor

From T. N. Thies IBMJRD (2000)

From Mayer and Lau (1990)

Inside an Integrated CircuitMaterials Science:Interdiffusion, anisotropic etching,electromigration, diff. therm. exp.

Condensed-matter Physics:Quantum Hall effects, quantum interference, non-local transport

Integer Quantum Hall Effect

1985 Nobel Prize Von Klitzing

Fractional QHE

1998 Nobel PrizeLaughlin, Tsui, Stormer

A very rich area ofCMP for 2 decades,Anyons, Skyrmions,Coulomb drag …

Fractional QHE



Take-home lesson: It’s the excitations (stupid!); the low-lyingExcitations of a many-Particle system determineIts properties!

The Field-Effect Transistor

Photo-lithography(the birth of nano-tech)

http://www.hitequest.com/Kiss/VLSI.htm

From T. N. Thies IBMJRD (2000)

From Mayer and Lau (1990)

Inside an Integrated CircuitMaterials Science:Interdiffusion, anisotropic etching,electromigration, diff. therm. exp.

Condensed-matter Physics:Quantum Hall effects, quantum interference, non-local transport

Fractional QHE



Take-home lesson: It’s the excitations (stupid!); the low-lyingExcitations of a many-Particle system determineIts properties!

Vorlesung Quantum Computing SS ‘08

20

ENIAC

• Electronic Numerical Integrator And Computer• 17468 vacuum tubes• weight 20 t, power consumption 150 kW

1946


21

Moore’s law

http://www.intel.com/technology/mooreslaw/


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breaking the barrier?

We may be starting to see this flatten out, latest Intel processors are using a “32 nm” process, and they are planning for 22nm. Previous generations had used a “45nm” process.http://techreport.com/articles.x/18216

Ihr Benutzername

bildchen von ProzessorenTEM Aufnahmen...

Gold Nano-particles

Color varies with particle size (red stained glassFrom the middle ages uses gold nano-particles)

http://www.meliorum.com/gold.htm?gclid=CObsuZfvlJ4CFQOdnAodoEl-qA

Gold Nano-particles

Color varies with particle size (red stained glassFrom the middle ages uses gold nano-particles)

http://www.nsec.ohio-state.edu/teacher_workshop/Gold_Nanoparticles.pdf

For even more exciting applications see the Dragnea group site in IU Chem.:http://www.indiana.edu/~bdlab/research.html

Self-Assembly routes to nanomaterials

Nanostructures from Self-Assembly

This self-assembly can be used to make materials with molecular size control (e.g. MCM-41 and related silicates)

http://cae2k.com/photos-of-aloha-0/mcm-41.html

http://igitur-archive.library.uu.nl/dissertations/2003-0325-143241/inhoud.htm

Discovery of the Neutron

T&R Figure 12.1

Chadwick (1932, building on earlier work by Both and Becker, and later I. Curie, and Joliot) demonstrated that the unknown radiation must have a mass of the same order as the proton by measuring the energy of recoil nuclei of various mass.

Size of Nuclei

T&R Figure 12.2 R = ro A1/3

Trends in Nuclear Stability

See also: T&R Fig. 12.6Please note two things from this figure:1.The binding energy per nucleon peaks at 56Fe (CALM)2.Note the peaks at 4He 16O, and (to some extent) at 12C.

http://www.tutorvista.com/physics/binding-energy-per-nucleon

http://www.corrosionsource.com/handbook/periodic/periodic_table.gif

21018365486

Closing a shell-> Stable atom, high ionization

energy

Magic numbers in Nuclei(protons)

From E. Segre “Nuclei and Particles

Note the sharp drop in separation energy at atomic numbers of 9, 21, 29,51, and 83

Magic numbers in Nuclei(neutrons)

From E. Segre “Nuclei and Particles

Shell model for NucleiFrom E. Segre “Nuclei and Particles”

3-D Harmonic Oscillator

Spherical Square well

Trends in Nuclear Stability

T&R Figure 12.5See also Nudat2 at:http://www.nndc.bnl.gov/nudat2/

Types of Radiation

http://www.nndc.bnl.gov/nudat2/reColor.jsp?newColor=dm

Types of Radiation•Alpha ():

•4He nucleus; very easy to stop (paper,etc.)•Beta ()

•Electrons or positions, relatively easy to stop •NOTE: you can also get high-energy electrons through “internal conversion” and the Auger process, but strictly speaking, these do not come from beta decay, and are therefore not, technically, “beta” particles (even though they behave exactly the same way).

•Gamma ()•High-energy photons (of nuclear origin)

•X-rays•High-energy photons (of atomic origin)

•Neutron (n)•Protons, ions

Types of Nuclear Decay•Alpha ():

•4He nucleus;

•Beta ()•Electrons or positions, of nuclear origin

•Electron Capture•Gamma ()

•(gamma, internal conversion do not change nucleons). •Spontaneous fission•proton•Neutron (n)

http://library.thinkquest.org/3471/radiation_types.html

Examples

• What is the binding energy per nucleon of 56Fe?

• The mass of 12553I is 124.904624u and that

of 12552Te is 124.904425 u. What decay

mode is possible between these two nuclei?

Building a more complex molecule C 2

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