Find Fermi Level Pos. of Si w/ 6x1015 Donors & 2x1015 Acceptors @ 300K

In summary, the Fermi level of Si doped with 6 x 1015 cm-3 donors and 2 x 1015 cm-3 acceptors at 300 K will be closer to Ei due to the higher number of donors compared to acceptors, resulting in a semiconductor behavior similar to n-type. The equation for n-type is used to calculate the Fermi level in this case.
  • #1
magnifik
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Si is doped with 6 x 1015 cm-3 donors and 2 x 1015 cm-3 acceptors. Find the position of the Fermi level with respect to Ei at 300 K.

i know the equations are
(for n-type) EF = kT ln(ND/ni) + Ei
(for p-type) EF = kT ln(ni/NA) + Ei

however, since the problem gives me both donors and acceptors, how do i know which one to use? i am thinking since there are more donors than acceptors, i use the equation for n-type...not sure if this is correct though.
 
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  • #2
All the acceptor states will be occupied by electrons come from donors. So the semiconductor will behave like n-type one with
[tex]
n'_{\text{donor}} = n_{\text{donor}} - n_{\text{acceptor}}
[/tex]
 

FAQ: Find Fermi Level Pos. of Si w/ 6x1015 Donors & 2x1015 Acceptors @ 300K

1. What is the significance of finding the Fermi level position in silicon with specific donor and acceptor concentrations at 300K?

The Fermi level is a key parameter in determining the electrical properties of a material, specifically its conductivity. In silicon, the Fermi level is important because it determines the concentration of electrons and holes, which are the charge carriers responsible for conductivity. By finding the Fermi level position, we can understand the overall conductivity and behavior of the material.

2. How do you calculate the Fermi level position in silicon with donor and acceptor concentrations?

The Fermi level position in silicon can be calculated using the following equation: EF = Ei + (kBT/q)ln(ND/ni), where Ei is the intrinsic energy level, kB is the Boltzmann constant, T is the temperature in Kelvin, q is the charge of an electron, ND is the donor concentration, and ni is the intrinsic carrier concentration.

3. How does the Fermi level change with increasing donor and acceptor concentrations in silicon?

The position of the Fermi level is directly related to the concentration of donors and acceptors in silicon. As the donor concentration increases, the Fermi level shifts closer to the conduction band, indicating a higher concentration of electrons. Similarly, as the acceptor concentration increases, the Fermi level shifts closer to the valence band, indicating a higher concentration of holes.

4. What is the effect of temperature on the Fermi level position in silicon?

The Fermi level in silicon is temperature-dependent, meaning it changes as the temperature of the material changes. As temperature increases, the intrinsic carrier concentration also increases, causing the Fermi level to shift towards the conduction band. This results in an increase in conductivity.

5. Can the Fermi level position in silicon be manipulated?

Yes, the Fermi level position in silicon can be manipulated by introducing impurities, such as donors or acceptors, into the material. This can be done through processes like doping, where specific impurities are intentionally added to alter the conductivity of the material. By controlling the concentration of these impurities, the Fermi level position can be adjusted, allowing for control over the electrical properties of the material.

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