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Give some Examples of direct and indirect band gap semiconductors?
direct band gap-semiconductor in which the bottom of the conduction band and the top of the valence band occur at the momentum k=0;in the case of d.b.s. energy released during band-to-band electron recombination with a hole is converted primarily into radiation (radiant recombination); wavelength of emitted radiation is determined by the energy gap of semiconductor; examples of d.b.s. GaAs, InP, ZnS, ZnSs, CdS, CdSe etc. indirect bandgap semiconductor --semiconductor in which bottom of the conduction band does not occur at effective momentum k=0, i.e. is shifted with respect to the top of the valence band which occurs at k=0; energy released during electron recombination with a hole is converted primarily into phonon; e.g. Si, Ge, GaP, GaAsp ,Ge etc, .
Are free electron in valence band or conduction band?
In semiconductors free electrons are in conduction bands.
What are excess carriers in semiconductors?
there excess carriers can dominate the conduction process in semiconductor material.
What are semiconductor diode laser describe with energy band diagram the construction and working of a semiconductor diode laser?
construction and working of semiconductor laser
What are the advantages of intrinsic semiconductor?
due to the poor conduction at room temperature,the intrinsic semiconductor as such,is not useful in the electronic devices.hence,the current conduction capability of the intrinsic semi conductor should be increased. this can be achieved by adding a small amount of impurity to the intrinsic semi conductor
What is the relationship between the valence and conduction bands in semiconductor materials?
In semiconductor materials, the valence band is the highest energy band occupied by electrons, while the conduction band is the next higher energy band that electrons can move into to conduct electricity. The energy gap between the valence and conduction bands determines the conductivity of the semiconductor.
What is the difference between direct and indirect energy?
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
What is the difference between the band structure of a semiconductor and that of a metal?
In a semiconductor, the band structure has a small energy gap between the valence and conduction bands, allowing for some electrons to move from the valence band to the conduction band when excited. In a metal, there is no energy gap between the bands, allowing electrons to move freely throughout the material.
What is the narrow-band semiconductor?
A narrow-band semiconductor is a type of semiconductor material with a small energy gap between its valence band and conduction band. This small energy gap allows for electrons to move easily between the bands, making it suitable for applications such as optoelectronics and telecommunications.
What is a difference between forbidden energy gap depletion region in semiconductor?
forbidden energy gap or energy gap or band gap or band or Eg is the gap between the top of the valance band and bottom of the conduction band. If we apply the energy equivalent to Eg then the electrons in valance band will jump to the conduction band. Ravinder kumar meena stpi n depletion region is the region in semiconductor where there is depletion of free charge carriers.Ravinder kumar meena stpi n
Acceptor atom create in semiconductor crystals?
If an acceptor atom is placed in a pure semiconductor, it will accept one or more electrons from the valence band of the semiconductor. This will permit positive holes in the conduction band to carry electrical current - the overall result is that the material will behave as a p-type semiconductor.
What is the effect of temperature on an intrinsic semiconductor?
An intrinsic semiconductor is basically a pure semiconductor, though some might argue that a small amount of doping can still yield an intrinsic semiconductor. In the crystal structure of this material, there are very few electrons crossing the band gap into the conduction band, and this stuff doesn't want to conduct much current. But as temperature increases, more electron-hole pairs will appear as electrons jump that band gap and take up places in the conduction band. And if you guessed that increasing temperature will permit the intrinsic semiconductor to conduct current flow a bit better, you'd be right. The intrinsic semiconductor has a positive temperature coefficient. More heat, more conduction under the same conditions.
What is the name of two energy bands at which current is produced in silicon?
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.
What is the working principle of semiconductor laser?
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
Valence electron conductor also can be called?
A valence electron conductor can also be called a semiconductor. Semiconductors have a small but nonzero energy gap between the valence band and the conduction band, allowing them to conduct electricity under certain conditions.
What is the gap between valance band and conduction band in a semi conductor?
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.
Is doping is used to increase the conductivity of intrinsic semi conductor material?
Doping a semiconductor provides additional charge carriers to the material. The dopant atoms are easily ionized, and this provides the semiconductor with either free electrons in the conduction band or electron vacancies (or holes) in the valence band, both of which allow the semiconductor to conduct electricity.
