How Does Temperature Influence Charge Carriers in Semiconductors?

[sh0x]

Hi
Can someone help me with the following questions?
1. How does temperature affect the # of charge carriers in a semiconductor? Explain
2. The # of ______ electrons is equal to the # of electrons available for conduction. Why?
3. How do dislocations affect the mobility of electrons in metals?

If anyone can help me I would be eternally grateful

 

[Astronuc]

There is a nice discussion of electrical properties and materials, specifically Electrical Conduction, at - http://www.virginia.edu/bohr/mse209/chapter19.htm

A dislocation represents a distortion in the crystal lattice, and electrons are scattered by discontinuities in the material lattice.

The electrons with the least binding energy would be most readily available for conduction.

 

[thepatientmental]

!

1. Temperature affects the number of charge carriers in a semiconductor by increasing or decreasing the amount of energy available for the electrons to move. As temperature increases, more electrons are able to break free from their bonds and become charge carriers, leading to an increase in conductivity. Conversely, at lower temperatures, fewer electrons are able to break free and the conductivity decreases. This is due to the energy gap between the valence band and conduction band becoming smaller at higher temperatures, allowing more electrons to transition from the valence band to the conduction band.

2. The number of free electrons available for conduction is equal to the number of valence electrons in the outermost energy level of an atom. These valence electrons are able to move freely and conduct electricity, while the inner electrons are tightly bound to the nucleus and do not contribute to conductivity. Therefore, the number of valence electrons is equal to the number of free electrons available for conduction.

3. Dislocations, which are defects in the crystal structure of a metal, can affect the mobility of electrons by creating barriers or obstacles for the electrons to move through. These barriers can cause the electrons to scatter and slow down, reducing the overall mobility and conductivity of the metal. Additionally, dislocations can also trap electrons, preventing them from moving freely and further reducing conductivity. This is why materials with fewer dislocations tend to have higher conductivity.