Electron Drift Velocity in Semiconductors

In summary, the low electron density of a semiconductor allows for faster movement of conduction electrons compared to conductors. This is due to the need to maintain current, which is directly proportional to electron density and average drift velocity. Despite fewer electrons, the same amount of EMF results in higher speeds for each electron.
  • #1
Izero
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Homework Statement


"The low [electron] density of a semiconductor means that the conduction electrons travel much faster than they do in conductors."

In order to fully understand this, I feel that I need to know why this occurs.

Homework Equations


I = nAve

Where:
I = current
n = electron density
v = average drift velocity
e = charge on one electron

The Attempt at a Solution


I know that, mathematically, the electrons need to travel faster in order for the current to be maintained, since current is flow of charge per unit time. I understand from the equation why this is the case, and the numbers make sense. However, I can't understand why the electrons would move faster just because there are fewer of them, and why the current doesn't just fall when a semiconductor is inserted into a circuit.
 
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  • #2
Totally guessing here, but perhaps you have the same amount of EMF distributed among fewer electrons, resulting in a higher speed for each electron?
 

Related to Electron Drift Velocity in Semiconductors

What is electron drift velocity in semiconductors?

Electron drift velocity in semiconductors refers to the average speed at which electrons move through a semiconductor material under the influence of an electric field.

How is electron drift velocity calculated?

Electron drift velocity can be calculated by dividing the electric current by the charge and the cross-sectional area of the material. This is known as the drift velocity equation: v = I/(nqA), where v is the drift velocity, I is the electric current, n is the electron density, q is the charge of an electron, and A is the cross-sectional area.

What factors affect electron drift velocity in semiconductors?

The electron drift velocity in semiconductors can be affected by the strength of the electric field, the temperature of the material, and the type of material being used. Additionally, impurities and defects within the material can also impact the drift velocity.

How does electron drift velocity differ in semiconductors compared to conductors?

In semiconductors, the electrons have a lower drift velocity compared to conductors. This is because in semiconductors, the electrons are bound to the atoms and must overcome the energy barrier of the band gap to move, while in conductors, the electrons are free to move and are not bound by the same energy barrier.

Why is understanding electron drift velocity important in semiconductor research?

Understanding electron drift velocity is important in semiconductor research because it allows scientists to predict the behavior of electrons within the material. This is crucial in the development of new semiconductor devices and technologies, such as transistors and solar cells.

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