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Topic: Band structure


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In the News (Sun 21 Apr 19)

  
  NSM Archive - Gallium Nitride (GaN) - Band structure
Important minima of the conduction band and maxima of the valence band.
Brillouin zone of the face centered cubic lattice, the Bravais lattice of the diamond and zincblende structures.
The band structure differs only slightly from other spin-neglecting calculations.
www.ioffe.rssi.ru /SVA/NSM/Semicond/GaN/bandstr.html   (394 words)

  
  Energy band formation
The band structure is directly related to the crystal structure of the material.
The inclusion of band structure in Monte Carlo simulations is discussed in Shichijo and Hess.
In the case of very high field transport, which requires the better physical model of the full band structure, it is also possible to use a hybrid approach which treats the less energetic particles with the non-parabolic band formulation.
www.mtmi.vu.lt /pfk/funkc_dariniai/quant_mech/bands.htm   (1339 words)

  
  Electronic band structure - Wikipedia, the free encyclopedia
The uppermost occupied band in an insulator or semiconductor is called the valence band by analogy to the valence electrons of individual atoms.
This band gap is one of the most useful aspects of the band structure, as it strongly influences the electrical and optical properties of the material.
The band structure has been generalised to wavevectors that are complex numbers, resulting in what is called a complex band structure, which is of interest at surfaces and interfaces.
en.wikipedia.org /wiki/Electronic_band_structure   (1388 words)

  
 Watch case and band attachment structure - Patent 4856687
The structure according to claim 1 wherein the fold between the base wall and the bending wall is struck along a line of the fold so as to reduce the thickness of the fold for facilitating bending.
The structure according to claim 1 wherein a center portion of the bending wall is bent so as to cause a fold in the direction of the width of the band so that the upper surface of the bending wall agrees with the shapes of the top portions of the side walls.
The base wall 5c of the connector 5 is attached to an underside 4c of a band end 4a, and from one end of the base wall 5c, a bending wall 5d extends and is bent so as to cause a fold 5e in the direction of the width of the band.
www.freepatentsonline.com /4856687.html   (1352 words)

  
 Band Structure Diagrams
An additional motivation to understand band structures is given by the fact that such knowledge is often needed to effectively communicate with condensed matter physicists, many of whom are very good at calculating band structures.
In summary remember that the band positions are determined by the energies of the atomic orbitals and the overlap of orbitals within a molecule.
The width of the bands is determined by the overlap of orbitals with neighboring molecules (intermolecular overlap).
www.chemistry.ohio-state.edu /~woodward/ch754/bandstr.htm   (1610 words)

  
 TRANSPARENT METALLO-DIELECTRIC PHOTONIC BAND GAP STRUCTURE (WO9915922A2)
In particular, this invention relates to a transparent metal device that utilizes a photonic band gap structure to transmit a selected range of wavelengths of the electromagnetic spectrum, such as the visible range, and to reflect all longer wavelengths.
By utilizing a PBG structure, the shielding device can include thick metal layers to provide a greater degree of isolation of unwanted radiation than for similar metal layer based filters that are not designed to take advantage of photonic band gap effects.
The present invention provides an apparatus and method to fabricate a transparent metallic structure that possesses the properties of a transparent glass in the visible portion of the electromagnetic spectrum, yet is opaque for all longer wavelengths (or smaller frequencies) from infrared light to radio waves.
www.delphion.com /details?&pn10=WO09915922A2   (1129 words)

  
 Lap Band - Physical Structure of Magical Device
Band- The physical structure of band is like a wristwatch.
For the adjustment of lap band saline in filled into it through a tube attached with it.
The lap band instrument is not new; the first lap band was developed by Obtech Medical in 1985 in Sweden.
www.lapbandslim.com /lap-band.html   (232 words)

  
 The Brass Crest: Band Structure and Organization
Youth bands usually require that members attend a corps regularly and be of the proper age.
A “Band Board” is a committee that oversees the operations of a band.
For a corps band, the corps officer is the de facto executive officer.
www.brasscrest.com /basics/bas04.html   (479 words)

  
 1. Crystal structures
In the simplest crystals the structural unit is a single atom, as in copper, silver, gold, iron, aluminium, and the alkali metals.
The band structure is directly related to the crystall structure of the material.
Band structure calculation of a real lattice is much more complicated and this exemple should be looked upon as a simple demonstration.
people.deas.harvard.edu /~jones/ap216/lectures/ls_2/ls2_u7/sse_tut_1/solid1.html   (1687 words)

  
 ECCC7 : A radical cure : Band structure of Liquid Water "
Band theory is a one-electron theory and as such neglects electron correlation.
One theoretical approach to understand the electronic structure of water, as a condensed medium, is to use the theory develloped for amorphous semiconductors [Williams 76].
While the amount of orbital overlap which creates the band structure might be different in water and in various forms of ice, it allows to separate out the instrinsic structure from the "extrinsic" structure caused by native defects.
www.ensta.fr /~muguet/papers/ECCC7/band.html   (2858 words)

  
 Semiconductors
The magnitude of the band gap depends primarily on the same factor that determines the separation in energy between the bonding and antibonding orbitals in an isolated molecule; namely, the strength of the bonds between adjacent atoms.
The Band Width (the spread of energies within the valence or conduction bands) is determined by the strength of the weak interactions between non nearest-neighbor atoms (i.e.
Gallium arsenide, GaAs, has the zinc sulfide structure (see figure 9 of lecture 3), which is identical to the "diamond" structure exhibited by germanium, except that the germanium atoms are replace by alternate gallium and arsenic atoms.
www.owlnet.rice.edu /~chem122/lecture/Reading/semibands.html   (881 words)

  
 Apple - iLife - GarageBand
Bring the band together and let Magic GarageBand generate a new song.
Playing along with the band is a perfect way to practice or create new songs.
By defining the structure of your song, you can quickly make broad changes to it later.
www.apple.com /ilife/garageband   (987 words)

  
 The band structure of bulk silicon   (Site not responding. Last check: )
To illustrate the basic principles, it is sufficient to calculate and plot the band structure for a small portion of the Brillouin zone.
The power of NanoLanguage, however, easily enables you to create a script that generates and plots the band structure for the entire zone, for example in order to produce a plot similar to the one shown for silicon in figure.
The figure to the right shows the obtained band structure of silicon, which indicates that silicon would have an indirect band gap of approximately 2 eV.
www.atomistix.com /manuals/ATK_2.1-beta-2/html_doc/ManualATK_2_1BulkSiExampleCreatingAndInspectingBulkConfiguration.html   (3041 words)

  
 A New Gap-Opening Mechanism in a Triple-Band Metal
Of three bands in the metal, one disappears after donating its electrons to a second in which a gap opens up, while the third opens a band-gap in the normal way.
Bands are indicated by bright regions of higher photoemission intensity.
The team found that in the insulating state below 125 K, the expected band-gap opening of the half-filled band was accompanied by a restructuring in which the band with the smallest filling disappeared, owing to an interband interaction in which the electrons of the disappearing band transferred into the third band, which became half filled.
www-als.lbl.gov /als/science/sci_archive/93indium.html   (995 words)

  
 Tight-binding electronic band structure of single-walled carbon nanotubes
The electronic band structure of carbon nanotubes is usually obtained by zone-folding of the π-band tight-binding band (πTB) structure of graphene.
A four-electron TB model, in which the overlap between orbitals on adjacent atoms is neglected (an orthogonal TB model), already yields differences between the zone-folded band structure and the band structure of the particular nanotube due to σ*-π* rehybridization effects (Fig.
Finally, it is a wide-spread practice in the band structure calculations to use the nanotube structure obtained by rolling up graphene into a cylinder ("rolled-up" nanotube structure).
www.phys.uni-sofia.bg /~vpopov/elbscomp.htm   (306 words)

  
 Principles - Some semiconductor physics - Band structure
The next higher band is the conduction band which is separated from the valence band by the energy gap, or bandgap.
Four of the five outer electrons are used to fill the valence band and the one extra electron from each impurity atom is therefore promoted to the conduction band.
The electrons in the conduction band are mobile, and the crystal becomes a conductor.
www.soton.ac.uk /~solar/intro/tech3.htm   (504 words)

  
 BP's Dictionary
Band Director, Head- Underpaid yet fanatically dedicated Commander-in-Chief of the band (whose wisdom and authority in the band hall can only be compared to that of a major deity), most Associate Band Directors want to become one.
Disqualification- 1) When a band member is barred from participating in band activities due to failure to meet academic standards, fear of this may inspire band members to study, 2) The barring of a band from competition due to a rules violation, see Eligibility.
Listening- Technique (in which many band members are unskilled) employing the ears to judge one’s pitch relative to the band or to comprehend spoken directions of the band director.
www.bandparenting.net /dict.html   (11082 words)

  
 Photonic Crystals
Photonic band gap crystals (PBG), due to their photonic band gap, which is similar to energy band gap for electrons in solid materials, have attracted much attention, especially in the field where an overlap of interests among photonics and electronics was unavoidable.
Altering the geometry of the voids, in such a way as to increase the symmetry of the periodic structure, the band gap can be restored in a low refractive index material.
The ideal structure to have is a three-dimensionally periodic photonic crystal (simply referred to here as a three-dimensional photonic crystal) with a full band-gap in three-dimensions.
www.mtmi.vu.lt /pfk/funkc_dariniai/nanostructures/photonic_crystals.htm   (1197 words)

  
 Kovar/Hall   (Site not responding. Last check: )
My careful theoretical modeling and painstaking experimentation reveal 1) that my equipment is crap, as are all the available texts on the subject and 2) that this whole exercise was a complete waste of my time.
Electrons in germanium are confined to well-defined energy bands that are separated by "forbidden regions" of zero charge-carrier density.
The upshot is that if you heat up a sample of germanium, electrons will jump from a non-conductive energy band to a conductive one, thereby creating a measurable change in resistivity.
www.cs.wisc.edu /~kovar/hall.html   (529 words)

  
 DAMOCLES: The physics -- band structure and scattering rates
The 'bottom' of the conduction band, where "thermal", "cold" electrons reside, is close to the symmetry point labeled X. The zero of the energy - an arbitrary quantity - has been made to coincide with the top of the valence band, at the symmetry point labeled Gamma.
In the figure energies are negative, by convention, for holes (carriers in the valence bands) and positive (and shifted by the band-gap, 1.17 eV, from the zero of the energy scale) for electrons.
At the temperature of liquid nitrogen (77 K) scattering with the lattice vibrations is less frequent than at room temperature (300 K), because the Si ions are subject to a smaller amount of thermal agitation and perturb less the motion of the carriers.
www.research.ibm.com /DAMOCLES/html_files/phys.html   (883 words)

  
 Generate new band structure
Basically, version of Matthias produced correct band edge for heavy and light hole, but noncorrect for s/o band (it was the same as for the light hole).
If absolute energies of unstrained bands are equal, some modifications are needed to keep at least the same number of new bands as old bands.
GaAs) the conduction band minimum lies at the Gamma point and is thus only affected by the absolute (hydrostatic) deformation potential which shifts the band energy accordingly.
www.wsi.tu-muenchen.de /nextnano3/structure/block_2/generate_new_band_structure.htm   (2079 words)

  
 Session V30 - Semiconductor Band Structure.
Remarkably, the band alignment is found to be almost the same for all those samples with a non negligible concentration of coordination defects in the amorphous region, whereas it is sizeably different for a defect-free sample.
The explanation of this result is ascribed to the semi-metallic behaviour of the defect-rich a-Si in the former case, and to the establishment of a ``genuine'' semiconductor/semiconductor type of interface in the latter.
Its crystal structure is rather complex, monoclinic with the space group C 2/m and with 36 atoms in the unit cell.
flux.aps.org /meetings/YR01/MAR01/abs/S7800.html   (2530 words)

  
 Band Structure of `BeB2'
The bands for Be from -17 eV to +8 eV.
The bands for Be from -1.5 eV to +1 eV.
The band structure of Be is qualitatively the same as before, but the band gap has nearly doubled.
www.phys.lsu.edu /faculty/browne/beb2.html   (375 words)

  
 Silicon Germanium (SiGe) Bands
The reader is therefore warned that there are many papers in the literature with the incorrect band alignments and band structure.
The figure on the right hand side is of the conduction band discontinuity between a relaxed virtual substrate Ge content on the left axis compared to an active heterolayer on the bottom axis.
The figure on the left hand side is of the valence band discontinuity between a relaxed virtual substrate Ge content on the left axis compared to an active heterolayer on the bottom axis.
www.sp.phy.cam.ac.uk /~SiGe/Bands.html   (357 words)

  
 Band structure, mobility, effective mass, holes
This method of viewing band formation is instructive, as it illuminates the mechanism of filling of the bands by electrons, according to the Pauli Exclusion Principle for fermions.
The empty band is separated from the valence band by a forbidden gap.
The width of the band gap is 6eV in the case of diamond.
psi.phys.wits.ac.za /teaching/Connell/phys284/2005/lecture-07/lecture_07/node5.html   (1283 words)

  
 DAMOCLES: Numerical algorithms -- Band structure and scattering rates
The inclusion of the spin-orbit interaction -- necessary for the valence bands -- has required a re-working of the band structure and the nonlocal approximation has been adopted for the valence bands of those materials for which hole transport has been implemented.
A transition to the nonlocal band structure will occur as necessity requires it: High-energy optical processes in Si, for example, can be better investigated with more accurate splittings at the symmetry points that nonlocal pseudopotentials provide.
Values labeled 'intra-band 1' are relative to intra-band transitions within the lowest-lying conduction band, those labeled 'inter-band and intra-high-bands' are relative to all other transitions, intraband within higher-energy bands and all inter-band processes.
www.research.ibm.com /DAMOCLES/html_files/numerics.html   (2537 words)

  
 The Woodpile Structure
It was clear that such structures would be much easier to fabricate than the intersecting cubic lattice, and it was my intuitive feeling that they would have large complete gaps at easily attainable index contrasts.
For this reason, Sami was not willing to publish the complete band structure on the four-layer cell until he could run some more tests on the code to ensure that convergence was obtained and that the gaps were real.
They gave detailed band calculations for the four-layer unit cell that were correct, they were the first to actually reduce the idea to practice in many fine experiments, and they were the first to patent the structure.
phys.lsu.edu /~jdowling/woodpile.html   (1114 words)

  
 NanoEd Resource Portal - Nanoconcepts and Applications
Band Structure of Carbon Nanotubes in a Perpendicular Electric Field
This interactive simulator performs band structure calculations for zigzag and armchair type carbon nanotubes (CNT) using the nearest-neighbor tight-binding method with a hopping potential of - 2.5eV.
For each structure, the simulator performs eigenvalue solutions for 51 values of the quasi-momentum k, evenly spaced in the allowed range.
www.nanoed.org /concepts_apps/cnt_band_field.html   (245 words)

  
 Band structure by effective-mass approximations   (Site not responding. Last check: )
The most important contribution to the effective mass for the conduction band minimum and valence band maxima is the energy gap
The form of unperturbed wave functions and matrix elements are assumed/fitted to reproduce the band structure around zone centers.
The EM results are obtained with a universal quantity for all the materials for the matrix elements and the band gap for each material.
www.physics.ohio-state.edu /ohmms/pubs/esnano/foil13.html   (85 words)

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