Mobility of electrons and holes

In summary, the conversation discusses the calculation of mobilities of electrons and holes in grey tin, silicon, and germanium assuming they are equal. It also mentions the necessary mobility for diamond to have an intrinsic conductivity of 10-12 S m-1 with equal mobilities for electrons and holes. The formula used is \sigma = Nc (e\mun*e\mup)exp(−Eg /2kT), with the given values for e, k, T, Nc, and Eg for each material. There is a mention of rearranging the formula and a minor mistake in using the wrong values initially.
  • #1
Distr0
10
0
Problem:
Calculate mobilities of electrons and holes (assuming equal) in grey tin, silicon and germanium. Calculate also the mobility that would be necessary for diamond to have an intrinsic conductivity of 10-12 S m-1 if the hole and electron mobilities were equal.

Working:
[tex]\sigma[/tex] = Nc (e[tex]\mu[/tex]n*e[tex]\mu[/tex]p)exp(−Eg /2kT)

[tex]\sigma[/tex]= 10-12
e = 1.6*10 -19
k = 1.38*10 -23
T = 300K
Nc = 2.5*1025
Eg(tin) = 0.08
Eg(silicon) = 1.11
Eg(germanium) = 0.66

For tin
Rearrange to give:

[tex]\mu[/tex]np = [tex]\sigma[/tex] / 2e Nc exp(−Eg /2kT)

The exponential becomes equal to zero...

I'm quite sure I'm missing something relatively simple here but not sure what
 
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  • #2
It appears i was using wrong values for the conductivity and Boltzmann constant, got the correct answer now.
 

What is the difference between mobility of electrons and holes?

Electron mobility refers to the ease at which electrons can move through a material when subjected to an electric field. On the other hand, hole mobility refers to the ease at which vacancies created by electrons can move through a material in the opposite direction of the electric field.

How does temperature affect the mobility of electrons and holes?

As temperature increases, the mobility of both electrons and holes decreases. This is due to the increased scattering of particles at higher temperatures, which makes it more difficult for them to move through the material.

What factors can influence the mobility of electrons and holes?

The mobility of electrons and holes can be influenced by various factors such as temperature, impurities in the material, and the crystal structure of the material. Additionally, the presence of electric and magnetic fields can also affect mobility.

What is the relationship between mobility and conductivity?

Mobility and conductivity are directly related, as mobility is a measure of how easily charges can move through a material, while conductivity is a measure of how well a material can conduct electricity. Higher mobility results in higher conductivity.

How is the mobility of electrons and holes measured?

The mobility of electrons and holes can be measured using a technique called Hall effect. This involves applying a magnetic field to a material and measuring the change in voltage across the material, which is directly related to the mobility of charges within the material.

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