Exploring Fermi Level in Compound Semiconductors

In summary, the Fermi level is the chemical potential of electrons at T=0K and is typically defined in metals due to the half-filled band condition. However, it is commonly said that in semiconductors, the Fermi level is located at the halfway point of the band gap. This can be found in introductory solid state textbooks. It is also possible to calculate the Fermi level in compound semiconductors such as GaN and Ce doped GaN. When in contact with a metal, the Fermi level can be used to determine the chemical potential of the semiconductor at T=0K. Temperature greens functions can be used to calculate the Fermi level at different temperatures.
  • #1
Naveeddd
3
0
Aasslam u alaikum to all,
i have confusion in knowing that " how fermi level form in a compound semiconductors e.g GaN, GaAs, etc.
Thanks to all
 
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  • #2
Strictly speaking the fermi level can be defined only in metals, because of the condition of half-filled bands. However usually it is said that the fermi level in the semiconductors lies at the half of the band gap; this fact is reported in every introductory solid state test. Maybe in one of these books you can also find a plausible explanation about.
 
  • #3
This question should be a FAQ, maybe you search for older threads.
The Fermi level is the chemical potential of the electrons at T=0K. So it is well defined even for semi-conductors and isolators.
 
  • #4
Davide86 said:
Strictly speaking the fermi level can be defined only in metals, because of the condition of half-filled bands. However usually it is said that the fermi level in the semiconductors lies at the half of the band gap; this fact is reported in every introductory solid state test. Maybe in one of these books you can also find a plausible explanation about.
thank you for help.
but i have stil confusiuns that how i can find value of fermi level in GaN and later in Ce doped GaN.
how does fermi level can lei in mid of the band gap? as there are no number of energy levels?
 
  • #5
DrDu said:
This question should be a FAQ, maybe you search for older threads.
The Fermi level is the chemical potential of the electrons at T=0K. So it is well defined even for semi-conductors and isolators.
thanks
can u calculate the value of fermi level in "GaN" a compound semeconductor?
 
  • #6
usually, it is not in the mid of the band gap but only somewhere in the band gap.
You can imagine as follows: When you bring a metal in contact with your semiconductor, then no electrons will flow from the semiconductor to the metal or vice verse if the chemical potential of the metal coincides with that of the semiconductor. Then you take the mimit T to 0. I suppose it can be calculated from temperature greens functions.
 

1. What is Fermi level in compound semiconductors?

The Fermi level in compound semiconductors is a measure of the energy at which electrons have a 50% probability of being occupied. It represents the highest possible energy level for electrons at absolute zero temperature and is a key concept in understanding the electrical properties of semiconductors.

2. How does the Fermi level in compound semiconductors affect conductivity?

The position of the Fermi level in compound semiconductors has a direct impact on the conductivity of the material. When the Fermi level is close to the conduction band, there are more free electrons available for conduction, resulting in higher conductivity. Conversely, when the Fermi level is close to the valence band, there are fewer free electrons for conduction, leading to lower conductivity.

3. How is the Fermi level controlled in compound semiconductors?

The Fermi level in compound semiconductors can be controlled through the addition of impurities, also known as doping. Doping introduces either donor or acceptor atoms into the semiconductor, which can shift the position of the Fermi level towards the conduction or valence band, respectively.

4. What is the difference between the Fermi level in intrinsic and doped compound semiconductors?

In intrinsic (undoped) compound semiconductors, the Fermi level is located at the middle of the band gap. However, in doped compound semiconductors, the Fermi level is shifted either towards the conduction band (n-type doping) or the valence band (p-type doping), depending on the type of dopant added.

5. How does temperature affect the Fermi level in compound semiconductors?

As temperature increases, the position of the Fermi level in compound semiconductors shifts towards the conduction band. This is due to the increasing number of thermally excited electrons that are able to occupy higher energy states, leading to a higher probability of electrons being present at the Fermi level.

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