Calculate the quasi-Fermi level of holes and electrons?

In summary, the conversation discusses the effective density of states for the conduction and valence bands of GaAs, as well as its band gap. The conversation also touches on the calculation of the quasi-Fermi levels for a system with a steady state density of electrons and holes. Several equations are mentioned, but the accuracy of these equations is questioned. The person speaking suggests that this topic may be more suitable for the advanced physics forum.
  • #1
yeyintkoko
16
0

Homework Statement


GaAs has an effective density of states (DOS) = 4 × 1017 cm−3 for the conduction band, = 8 × 1018 cm−3 for the valence band and a band gap of = 1.42 eV.
a) A thin slice of GaAs is illuminated by a cw light source, creating a steady state
density of 1017 cm−3 of electrons and holes. Calculate the quasi-Fermi level of
holes and electrons for the system.

Homework Equations


ni = (NCNV)1/2 (-EG/2kT);
Ei = EG/2 + kT/2 * ln(NV/NC);

Efc-Ei = kTln(n/ni);
Efv-Ei = -kTln(p/ni);

Efc-Ei = kTln(1017/ni);
Efv-Ei = -kTln(1017/ni);

The Attempt at a Solution


My problem is that this equations is right?
 
Last edited:
  • #3
IMO this belongs in the advanced physics forum.
 

Related to Calculate the quasi-Fermi level of holes and electrons?

1. What is the quasi-Fermi level of holes and electrons?

The quasi-Fermi level of holes and electrons is a concept used in semiconductor physics to describe the energy levels of these charge carriers in a material. It represents the average energy at which these carriers are present in the material and is influenced by factors such as temperature and applied voltage.

2. How is the quasi-Fermi level of holes and electrons calculated?

The quasi-Fermi level of holes and electrons can be calculated using the following formula:
QFL = EF + kTln(NV/ni) + kTln(NC/ni)
where QFL is the quasi-Fermi level, EF is the Fermi level, k is the Boltzmann constant, T is the temperature, NV and NC are the density of states in the valence and conduction bands, respectively, and ni is the intrinsic carrier concentration.

3. What is the significance of the quasi-Fermi level in semiconductor devices?

The quasi-Fermi level is an important concept in understanding the behavior of charge carriers in semiconductor devices. It helps to determine the direction and magnitude of carrier flow, as well as the efficiency of carrier transport and recombination. It is also used in the design and optimization of semiconductor devices.

4. How does temperature affect the quasi-Fermi level of holes and electrons?

In general, as temperature increases, the quasi-Fermi level of both holes and electrons also increases. This is because higher temperatures provide more thermal energy for the carriers, allowing them to reach higher energy levels. However, the exact relationship between temperature and QFL may vary depending on factors such as the doping concentration and type of semiconductor material.

5. Can the quasi-Fermi level of holes and electrons be changed by an applied voltage?

Yes, the quasi-Fermi level of holes and electrons can be changed by an applied voltage. This is because an applied voltage can alter the energy levels and distribution of charge carriers in a semiconductor material, thereby affecting the QFL. This is a key principle in the operation of semiconductor devices such as diodes and transistors.

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