Electron-hole gas density in different materials

In summary, when two metals with different Fermi levels are connected, electrons will flow from the metal with the higher Fermi level to the one with the lower level until the lower one becomes negatively charged. However, if two materials with different Fermi levels and equal conductivity for both electrons and holes are connected, holes may also be transferred between them. The definition of a hole in a metal is unclear. While some metals, such as aluminium, may have a positive Hall coefficient, this does not necessarily indicate that the charge carriers are holes.
  • #1
Stanley514
411
2
If we connect a two metals with different Fermi levels electrons will start to flow from metal with higher Fermi level to a lower one. Untill metal with lower Fermi level will get negatively charged and the process will stop.
But what if we connect a two materials with different Fermi levels, but equal conductivity of both electrons and
holes? Will holes start to get transferred between these materials too, and if yes, how exactly?
 
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  • #2
How do you define a hole in a metal?
 
  • #3
I do not know, but does positive Hall coefficient in metals exists?
 
  • #4
It does, for example in aluminium. But this does not mean that the charge carriers are holes.
 
  • #5
DrDu said:
It does, for example in aluminium. But this does not mean that the charge carriers are holes.
What then?
 

1. What is an electron-hole gas?

An electron-hole gas is a state of matter where free electrons and positively charged vacancies, known as holes, coexist in a material. This state arises when an external energy source, such as light or heat, excites electrons from their bound states, leaving behind holes in the material.

2. How does the density of an electron-hole gas vary in different materials?

The density of an electron-hole gas depends on the material's band structure, which is determined by the atomic and electronic properties of the material. In general, materials with wider band gaps tend to have lower electron-hole gas densities, while materials with narrower band gaps have higher densities.

3. What factors influence the electron-hole gas density?

The electron-hole gas density is affected by various factors, including the material's composition, temperature, and external energy sources. Additionally, the density can be tuned by doping the material with impurities, which can introduce additional electrons or holes into the system.

4. How is the electron-hole gas density measured?

The electron-hole gas density is typically measured using techniques such as photoluminescence spectroscopy, where the emission of light from the material is used to determine the concentration of free electrons and holes. Other methods include Hall effect measurements and capacitance-voltage measurements.

5. What are the potential applications of controlling the electron-hole gas density?

Controlling the electron-hole gas density in materials has potential applications in fields such as optoelectronics, photovoltaics, and semiconductor devices. By manipulating the number of free electrons and holes, the electrical and optical properties of materials can be tuned for specific applications.

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