Doped Semiconductors: Comparing Silicon & Germanium

In summary, the band gaps of silicon and germanium are 1.1Mev and 0.6Mev respectively, with silicon having a larger donor area energy of 25Mev compared to germanium's donor energy of 2Mev. This means that it is harder for electrons to move into the conductive band in silicon. To determine which material is more likely to have intrinsic and extrinsic carriers in the conduction band at room temperature, one would need to consider the impurity levels and their energies, which are typically in the range of tens of millielectronvolts. As for the effect of temperature, the behavior of intrinsic and extrinsic carriers in the conduction band would change accordingly.
  • #1
oddiseas
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If we have two semiconducting materials say silicon and germanium and in this specific case silicon has a very large donor area energy say 25Mev and a very small energy gap, say 1.1Mev and germanium has a smaller energy gap then silicon, 0.6Mev and a donor energy of 2Mev.

I amtrying to figure out the logic of this.Does having a larger donor area energy mean that it is harder for the electrons to move into the conductive band?

And how would i figure out which is more likely to intrinsic and extrinsic carriers in the conduction band at room temperature?

and how would this change with increasing temperature?
 
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  • #2
oddiseas said:
If we have two semiconducting materials say silicon and germanium and in this specific case silicon has a very large donor area energy say 25Mev and a very small energy gap, say 1.1Mev and germanium has a smaller energy gap then silicon, 0.6Mev and a donor energy of 2Mev.

I amtrying to figure out the logic of this.Does having a larger donor area energy mean that it is harder for the electrons to move into the conductive band?

And how would i figure out which is more likely to intrinsic and extrinsic carriers in the conduction band at room temperature?

and how would this change with increasing temperature?

Er... MEGA electron volts?!

Zz.
 
  • #3
The band gaps shown in your post are in eV (and not MeV - megaelectron volts).
The energies of the donor levels are much lower, of the order of tens of millielectronvolts (meV). Maybe a confusion regrading the notations?
Kittel gives the energy of the impurity levels in meV, for example.
 

1. What is the difference between silicon and germanium?

Silicon and germanium are both chemical elements in the same group on the periodic table, but they have different atomic structures. Silicon has a diamond-like crystal structure, while germanium has a more complex diamond cubic structure. Additionally, silicon is more abundant in nature and has a wider bandgap compared to germanium, which makes it a better semiconductor for many applications.

2. What are doped semiconductors?

Doped semiconductors are materials that have impurities intentionally added to their structure. These impurities, also known as dopants, are atoms of different elements that have either more or fewer valence electrons than the atoms in the base semiconductor material. This results in the creation of free charge carriers, either electrons or holes, which can enhance the electrical conductivity of the semiconductor.

3. How does doping affect the properties of silicon and germanium?

Doping can significantly alter the electrical properties of silicon and germanium. When a dopant with more valence electrons is added, it creates an n-type semiconductor with an excess of negatively charged electrons. On the other hand, a dopant with fewer valence electrons creates a p-type semiconductor with an excess of positively charged holes. Doping also affects the bandgap of the semiconductor, which determines its ability to conduct electricity.

4. What are some common applications of doped silicon and germanium?

Doped silicon and germanium are widely used in the electronics industry, especially in the production of transistors and computer chips. They are also used in the manufacture of solar cells, which convert sunlight into electricity. Additionally, doped semiconductors are used in sensors, LEDs, and other electronic devices.

5. Which is a better semiconductor, silicon or germanium?

The answer to this question depends on the specific application. In general, silicon is considered a better semiconductor due to its wider bandgap, higher thermal stability, and lower cost. However, germanium has some advantages in certain applications, such as its higher electron mobility and its ability to absorb infrared light. Ultimately, the choice between silicon and germanium as a semiconductor depends on the specific requirements and limitations of the application.

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