Concept of HOLES and ELECTRONS

[Shashiketan]

HI,
I have a question that why we regard the conductivity in semiconductors both due to holes and as well as electrons.
the current density is nµ(electrons)+pµ(holes).
holes is a concept originated from electrons. when electrons move from one place to other we say current is produced. also, this creates holes.
The concept of holes and electrons is pretty much interrelated. how can we generate current due to holes and electrons differently??
Please answer.
Regards,

 

[Ratch]

Shashiketan,

I have a question that why we regard the conductivity in semiconductors both due to holes and as well as electrons.

You have come to the right place.

the current density is nµ(electrons)+pµ(holes).

That above is only the drift current density. There is also the diffusion current density which is -q*Dp*del(p)+q*Dn*del, where Dn and Dp are the electron and hole diffusion constants respectively, and del,del(p) are the gradients of the n and p concentrations respectively.

holes is a concept originated from electrons. when electrons move from one place to other we say current is produced. also, this creates holes.
The concept of holes and electrons is pretty much interrelated.

Are you answering your own question?

how can we generate current due to holes and electrons differently??

In the English language, the beginning word of each sentence is capitalized. It makes it a lot easier to read.

At the quantum level, holes have the same status of as electrons, including an effective mass. Holes are only found in semiconductor material. You can read how this is done by doping the intrinsic semiconductor material.

Holes are positive charge carriers. Negative charge carriers like electrons moving in one direction are equivalent to holes moving in the opposite direction. So to answer your question, holes and electrons become current when they move because they are moving charge carriers.

Ratch

 

[Shashiketan]

Shashiketan,



You have come to the right place.



That above is only the drift current density. There is also the diffusion current density which is -q*Dp*del(p)+q*Dn*del, where Dn and Dp are the electron and hole diffusion constants respectively, and del,del(p) are the gradients of the n and p concentrations respectively.



Are you answering your own question?



In the English language, the beginning word of each sentence is capitalized. It makes it a lot easier to read.

At the quantum level, holes have the same status of as electrons, including an effective mass. Holes are only found in semiconductor material. You can read how this is done by doping the intrinsic semiconductor material.

Holes are positive charge carriers. Negative charge carriers like electrons moving in one direction are equivalent to holes moving in the opposite direction. So to answer your question, holes and electrons become current when they move because they are moving charge carriers.

yes true so current should be either nµ or pµ and not both?

 

[Ratch]

Shashiketan,

[QUOTE]Yes true, so current should be either nµ or pµ and not both? [/QUOTE]

Both drift and diffusion for each charge carrier.

J_n = q*µ_n*n*ξ + q*D_n*del
J_p = q*µ_p*p*ξ - q*D_p*del(p)
J_total = J_n+J_p

Ratch

 

[Shashiketan]

Shashiketan,

[QUOTE]Yes true, so current should be either nµ or pµ and not both?

Both drift and diffusion for each charge carrier.

J_n = q*µ_n*n*ξ + q*D_n*del
J_p = q*µ_p*p*ξ - q*D_p*del(p)
J_total = J_n+J_p

Ratch[/QUOTE]

Sorry to Say but i am Confused!!
the J_total should be either J_n or J_p and not J_n+J_p.
if you could get my question.

 

[juzar_3091986]

Kindly can someone reply to this question please sir

12.If an intrinsic semiconductor is doped with a very small amount of boron then the extrinsic semiconductor set formed ,the no. of electrons and holes will
A.both dec
B.increase and decrease
C.Both increase
D.Decrease and increase

 

[Ratch]

juzar_3091986,

If an intrinsic semiconductor is doped with a very small amount of boron then the extrinsic semiconductor set formed ,the no. of electrons and holes will

Nn*Np = Ni^2 Boron will increase the Nn concentration, so Np will decrease.

Ratch