Semiconductor Notation: P-Type, N-Type Band Gap Materials

[radaballer]

If you research the materials semiconductors are made of you will find things such as aluminum gallium arsenide. How do you determine what the p-type and n-type are made of? Shouldn't there be a structural difference in order to create band gap?

 

[Simon Bridge]

You want to avoid differences to the geometric structure if you can - or you get cracks and flaws in the crystal that mess up the electronics.

To make a specific type of semiconductor you start with the base crystal and then dope it.
The odd mixtures come from trying out different combinations and crystal growth techniques.

 

[ModusPwnd]

Most may want to avoid differences in geometric structure. My graduate research was about purposefully introducing differences in structure and exploring the novel characteristics that resulted. But then, our material no longer technically qualified as a "crystal".

To be clear, nothing I or my group was making was a commercial product. It was science, not engineering. :p

 

[Simon Bridge]

Neat - my graduate research was exactly the opposite - combining crystals with almost the same lattice constant and exploring the novel stuff that happened :)

 

[pmacias]

I can explain that the p-type and n-type designations in semiconductors refer to the type of doping used in the material. Doping is the process of intentionally adding impurities to a pure semiconductor material in order to alter its electrical properties. In p-type semiconductors, the impurities added are known as acceptors, which have one less valence electron than the atoms in the semiconductor material. This creates "holes" in the material, which act as positive charge carriers. In contrast, n-type semiconductors use donors, which have one extra valence electron, creating an excess of negatively charged electrons in the material.

The structural difference between p-type and n-type semiconductors lies in the type of impurities added and their arrangement within the material. For example, in aluminum gallium arsenide, aluminum is used as the acceptor impurity for p-type doping, while silicon or sulfur can be used as the donor impurity for n-type doping. The arrangement of these impurities creates a band gap, which is the energy difference between the valence band (where electrons are bound to atoms) and the conduction band (where electrons are free to move and conduct electricity).

In summary, the p-type and n-type designations in semiconductors refer to the type of doping used, which creates structural differences in the material and results in a band gap. The specific materials used for doping depend on the desired properties and application of the semiconductor.