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 = \frac{1}{nq}​

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

R_H = \frac{-1}{ne}​

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

 

[rwooduk]

hm so simple, many thanks!