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In semiconductors free electrons are in conduction bands.

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hoes are vacancies left by the electron in the valence band. hence there cannot be holes in the conduction band

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The quantum mechanical energy band where electrons reside in semiconductors that participate in electrical conduction.

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No. Conduction band is basically the unfilled energy levels into which electrons can be excited to provide conductivity.

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The band gap represents the minimum energy difference between the top of the valence band and the bottom of the conduction band, However, the top of the valence band and the bottom of the conduction band are not generally at the same value of the electron momentum. In a direct band gap semiconductor, the top of the valence band and the bottom of the conduction band occur at the same value of momentum.

In an indirect band gap semiconductor, the maximum energy of the valence band occurs at a different value of momentum to the minimum in the conduction band energy

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In a direct band gap the electron only needs energy to jump to the conduction band. In an indirect band an electron needs energy and momentum to jump to the conduction band

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The quantum mechanical energy band where electrons reside in semiconductors that participate in electrical conduction.

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The two energy bands in which current is produced in silicon are the valence band and the conduction band. Electrons in the valence band can be excited to the conduction band by absorbing energy, allowing them to move and create an electric current.

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Free electrons typically exist in the conduction band of a material's energy band structure. In the conduction band, electrons are not bound to any specific atom and are free to move and conduct electricity.

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The effective density of states in the conduction band refers to the density of electron states available for conduction. It is influenced by factors like the band structure of the material, temperature, and the presence of impurities or defects. It characterizes the number of conducting electrons that can participate in charge transport in a material.

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The electron configuration of rubber (natural of artificial is such that there is a big gap between valance band and conduction band of electrons. Electrons has to make a transition from valence band to conduction band in order to conduct electricity.

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if we increase the temp so large no of electrons jumbs from valence energy band to conduction energy band .when there are alarge no of electrons in conduction band to the conduction increase means this simiconductor can conduct easyly.

thanx

Engr Bashir Khan.

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Electrons in a conduction band.

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It gets hot.......... by magic

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Semiconductors, in the absence of applied electric fields, act a lot like insulators. In these materials, the conduction band and the valence band do not overlap. That's why they insulate. And that's why you have to apply some serious voltage to them to shove the valence electrons across the gap between the valence and conduction bands of these semiconductor materials. Remember that in insulators, there is a "band gap" between the lowest Fermi energy level necessary to support conduction and the highest Fermi energy level of the valence electrons. Same with the semi's. In metals, the conduction band overlaps the valence band Fermi energy levels. Zap! Conductivity.

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there will be only certain energy levels in which electrons get filled up. In valence orbitals there will be many such energy levels and the energy gap between conduction band and valence band is called energy band gap.

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Because it has a free electron in the conduction energy band.

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No. As temperature increases, resistance of semiconductors decrease.

This is because semiconductors have a small energy gap between their valence band and conduction band (in the order of 1 eV). Electrons must exist in the conduction band in order for the material to conduct but electrons exist in the valence band naturally. The electrons gain thermal energy for surroundings and jumps the energy gap from valence band to conduction band and hence, the SC material more readily conducts. As temperature increases, electrons can gain more thermal energy, more electrons can enter the conduction band and hence, resistance decreases.

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when electron is excited from valence band to conduction band

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The principle of semiconductor laser is very different from CO2 and Nd:YAG lasers. It is based on "Recombination Radiation"

The semiconductor materials have valence band V and conduction band C, the energy level of conduction band is Eg (Eg>0) higher than that of valence band. To make things simple, we start our analysis supposing the temperature to be 0 K. It can be proved that the conclusions we draw under 0 K applies to normal temperatures.

Under this assumption for nondegenerate semiconductor, initially the conduction band is completely empty and the valence band is completely filled. Now we excite some electrons from valence band to conduction band, after about 1 ps, electrons in the conduction band drop to the lowest unoccupied levels of this band, we name the upper boundary of the electron energy levels in the conduction band the quasi-Fermi level Efc. Meanwhile holes appear in the valence band and electrons near the top of the valence band drop to the lowest energy levels of the unoccupied valence energy levels, leave on the top of the valence band an empty part. We call the new upper boundary energy level of the valence band quasi-Fermi level Efv. When electrons in the conduction band run into the valence band, they will combine with the holes, in the same time they emit photons. This is the recombination radiation. Our task is to make this recombination radiation to lase

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Rubber bands are insulators because they are made of materials that have high electrical resistance, which prevents the flow of electricity through them. This property makes them effective at preventing electrical conduction and reducing the risk of electrical shock.

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The electronic energy band of a http://www.answers.com/topic/crystalline solid which is partially occupied by electrons.

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The single valence band electron can easily escape and become a conduction band electron.

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Conduction band - The unfilled energy levels into which electrons can be excited to provide conductivity.Valence band - The energy levels filled by electrons in their lowest energy states.

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The Fermi energy level in semiconductors is located midway between the conduction band and valence band due to the intrinsic nature of semiconductors. This positioning ensures that at thermal equilibrium, the probability of electrons being excited from the valence band to the conduction band equals the probability of electrons recombining from the conduction band to the valence band. This equilibrium state allows for the semiconductor to exhibit unique electrical properties.

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moving conduction band electrons

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Because it has a free electron in the conduction energy band.

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It is the band of energy of an electron in outer most orbit

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The forbidden energy gap is the energy difference between the valence band and the conduction band in a semiconductor, representing the energy needed for an electron to move from the valence band to the conduction band. The depletion region is a region near the junction of a semiconductor device where there are no free charge carriers. In this region, the forbidden energy gap plays a role in creating a potential barrier that prevents the flow of current.

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In a foam there is a large gap between the conduction band and the valence of band in the atoms makng up the foam. If any object is to conduct electricity through it the gap between the conduction band amd the valance should be minimun or overlapping so that the electrons in the valance band can go into conduction band and conduct electricity

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Process by which a conduction band electron gives up energy (in the form of heat or light) and falls into a valence band hole.

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Free electrons exist in the conduction band, which is the highest energy band in a material where electrons are free to move and conduct electricity.

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Semiconductive materials do not conduct current well because their valence band is mostly filled and their conduction band is mostly empty, requiring an input of energy for electrons to move from the valence to the conduction band and thus carry a current. Additionally, semiconductors have a wider band gap compared to conductors, which further restricts the flow of electrons.

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Optical sources like LEDs use direct band gap so that conduction band electorn can recombine directly with a hole in valence band .

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Lots of free electrons in conduction band. This is commonly referred to as the electron gas.

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Morris Day is band conduction of the Michael Basin show on TV.

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Electrons 'jump' from one atom to another. The electron configuration of the atoms determine how easy it is for an electron to move from one atom to another, which is a factor in determining conductivity of the substance.

Actually in atoms in the solid state, electrons occupy one of 2 quantum energy bands: the valence band or the conduction band. Valence band electrons are tightly bound to the atom, but conduction band electrons are not bound to the atom and can roam freely through the material.

  • insulators have very few if any conduction band electrons and thus cannot conduct
  • conductors have so many conduction band electrons that they form what is called an electron gas that fills all of the material and can flow freely, there is no"'jumping' from one atom to another" at all

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The energy band gap of germanium is approximately 0.67 electronvolts (eV). This means that it requires this amount of energy to move an electron from the valence band to the conduction band in germanium.

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The Fermi level moves to wherever it needs to be to assure that the overall

system is charge-neutral. In an n-type semiconductor, we introduce fixed

positive charges (donors), which must be balanced by mobile negative charges

(electrons). The excess electrons must reside in the conduction bands,

because the valence bands are full. To have excess electrons in the

conduction band, the Fermi level (electrochemical potential for electrons)

must lie near the conduction band. A similar argument can be made for

p-type doping

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Silicon is a semiconductor because it has four valence electrons in its outer shell, allowing it to easily form a crystalline structure. This structure enables silicon to conduct electricity better than an insulator but not as well as a conductor, making it suitable for use in electronic devices. Additionally, doping with other elements can further enhance its conductivity.

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The electrical conductivity of pure metals decreases with temperature because as temperature increases, the metal lattice vibrates more, causing more resistance against the flow of electrons. In semiconductors, as temperature increases, more electrons are promoted into the conductive band, increasing their conductivity.

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A conductor allows the flow of electricity due to the presence of free electrons, whereas an insulator restricts the flow of electricity due to the absence of free electrons. Conductors like metals have loosely bound electrons that can move freely, while insulators like rubber have tightly bound electrons that do not move easily.

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It gives the band a beat and tempo. In other words, a conductor is just a back- up drummer just in case the drummer sucks or there is no drummer.

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'Cause the conduction band of rubber are far away from each other.

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The number of energy levels in the 3s conduction band of a single crystal of sodium weighing 26.8 mg is enormous, on the order of Avogadro's number (6.022 x 10^23). This is due to the large number of atoms present in the crystal. Each sodium atom has one electron in its 3s orbital, leading to a vast number of energy levels in the conduction band.

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Normally, no electron energy states exist in the band gap, the gap between the valence band and conduction band in a semiconductor.

However, if we dope the semiconductor, i.e. add donor (n type) or acceptor (p type) atoms to it, we introduce new electron energy states in the band gap!

Take for example silicon, in which we introduce phosphorus, which is a group V element and thus a donor atom. This will introduce extra filled electron states just below the conduction band.

Now, this all happens at 0K, so no current can flow (this is logical as electrons don't move at this temperature, even with an electric field applied). But if we raise the temperature e.g. until room temperature at 300K, the electrons gain energy and can jump into the free energy states in the conduction band. These electrons in the conduction band can now conduct electricity.

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we all know that electrons,photons, phonons can excite an electron from valence band to conduction band...i think the main difference between electronic bandgap and optical bandgap is that in electonic its the energy required for an electron to move from the valence band to the conduction band.but in optical bandgap photons(packet of energy in the form of light waves) are assisting the electrons to move from valence band to conduction band.

The difference between optical and electronic bandgap is more complexe actually. The optical bandgap is the one that can be measured using optical techniques (based on transmission and reflection, i.e. Tauc plot). However, this measurement does not take into account all traps you might have within the bandgap that can modify the energy required to move one charge carrier from the conduction band ans the conduction band. The electronic band gap (which is the one of interest in fine, in an integrated device) is measured under operation. Thus, for many devices (lasers, solar cells...etc.) the electronic bandgap (energy required to get the device working) can defer from the optical bandgap.

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direct band gap means in e-k diagram valance bands are exactly below covalance band,in this band electron falls from the conduction band to valance band directly without going to metastable state and in indirect band gap the band electron falls from the conduction band to valance band by first going through the metastable state

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