How to identify if a semiconductor is n-type or p-type?

[rwooduk]

please see attached image for problem



if a dopant gives an electron it's an n-type, if a dopant takes an electron it's a p-type.



i can't see how to relate the hall coefficient value to the property of being a n-type or p-type semiconductor?

any pointers on this would really be appreciated, thanks

 

[mfb]

Electrons flowing in one direction will get deflected in the same direction as holes flowing in the opposite direction - for one doping type you get negative electrons at one side, for the other doping type you get positive holes at this side. This leads to a different hall coefficient.

 

[Jufro]

The Hall Coefficient is:

R_H = [itex]\frac{1}{nq}[/itex]​

For electrons, q= -e, and our hall coefficient is:

R_H = [itex]\frac{-1}{ne}[/itex]​

Therefore we know that n-type semiconductors have negative R_H.

 

[rwooduk]

hm so simple, many thanks!

 

[paranormal]

I understand your confusion about relating the Hall coefficient value to the type of semiconductor. The Hall coefficient is a measure of the material's response to an applied magnetic field and is not directly related to the type of semiconductor.

To determine if a semiconductor is n-type or p-type, we need to look at the dopants used in the material. As mentioned in the initial content, if a dopant gives an electron, it is considered an n-type semiconductor, and if it takes an electron, it is a p-type semiconductor.

Dopants are impurities intentionally added to the semiconductor material to change its electrical properties. For example, elements like phosphorus, arsenic, and antimony are commonly used as n-type dopants because they have an extra electron in their outermost shell, which can easily donate to the semiconductor's conduction band.

On the other hand, elements like boron, aluminum, and gallium are commonly used as p-type dopants because they have one less electron in their outermost shell, creating a "hole" that can easily accept an electron from the semiconductor's valence band.

Therefore, to identify the type of semiconductor, you can look at the dopants used in the material and their behavior regarding electron donation or acceptance. Additionally, other techniques such as Hall effect measurements, electrical conductivity, and thermoelectric measurements can also provide valuable information about the type of semiconductor.