Mobility of Electrons: Why are They More Mobile than Holes?

In summary, the conversation discusses why the mobility of electrons is greater than that of holes, despite the fact that electrons have a larger effective mass. The discussion focuses on the transport and DOS effective mass in Si and GaAs, noting that the valley degeneracy and anisotropy can affect these values. The significance of electron movement in generating holes is also mentioned, with a reminder to pay attention to the dates of the posts in the thread.
  • #1
sudeshiitr
3
0
why the mobility of electrons more than holes despite the fact that electrons have larger effective mass than holes.
 
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  • #2
What system are you talking about? In Si and GaAs, the (transport) effective mass of electrons is smaller than that of holes.

Note: In general, the transport effective mass will differ from the DOS effective mass, particularly if the valley degeneracy is not 1 or if there is a large anisotropy in the structure.
 
  • #3
I am talking about DOS effective mass...
 
  • #4
did anyone ever answer this question about the http://www.3gcgroup.com/" of the electrons?
 
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  • #5
Don't the electrons have to move in order for holes to move? How else do you get holes?
 
  • #6
johnsims said:
did anyone ever answer this question about the http://www.3gcgroup.com/" of the electrons?
Please pay attention to the dates of the posts, your last post was in a 6 year old thread, this one is 4 years old.
 
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Related to Mobility of Electrons: Why are They More Mobile than Holes?

1. Why are electrons more mobile than holes?

Electrons are more mobile than holes because they have a negative charge, which allows them to move more freely in an electric field. This is due to the fact that they are repelled by the negative charge and attracted to the positive charge, causing them to move towards the positive electrode with greater ease.

2. How does the band structure of a material affect electron mobility?

The band structure of a material plays a crucial role in determining the mobility of electrons. In materials with a wider bandgap, there is a larger energy barrier between the valence and conduction bands, making it more difficult for electrons to move. On the other hand, materials with a narrower bandgap have a smaller energy barrier, allowing electrons to move more easily.

3. What role do impurities play in electron mobility?

Impurities can significantly affect electron mobility in a material. When impurities are added to a material, they can create defects in the crystal lattice, which can act as scattering centers for electrons. This can hinder their movement and decrease their mobility.

4. How does temperature impact the mobility of electrons?

Temperature has a direct impact on the mobility of electrons. As the temperature increases, the atoms in the crystal lattice vibrate more vigorously, creating more scattering centers for electrons. This results in a decrease in electron mobility. Additionally, at higher temperatures, some electrons may gain enough thermal energy to break free from the crystal lattice, further reducing electron mobility.

5. Can electron mobility be improved in materials?

Yes, electron mobility can be improved in materials through various methods. One approach is to reduce the number of impurities in the material, which will decrease the number of scattering centers for electrons. Additionally, by carefully engineering the band structure of a material, it is possible to create a material with a larger bandgap, allowing for higher electron mobility.

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